Zettelstore

0.4
0.3

// ZettelNode is the root node of the abstract syntax tree.
// It is *not* part of the visitor pattern.
type ZettelNode struct {
	Meta    *meta.Meta     // Original metadata
	Content domain.Content // Original content
	Zid     id.Zid         // Zettel identification.
	InhMeta *meta.Meta     // Metadata of the zettel, with inherited values.
	Ast     BlockSlice     // Zettel abstract syntax tree is a sequence of block nodes.
	Ast     *BlockListNode // Zettel abstract syntax tree is a sequence of block nodes.
	Syntax  string         // Syntax / parser that produced the Ast
}

// Node is the interface, all nodes must implement.
type Node interface {
	WalkChildren(v Visitor)
}

// BlockNode is the interface that all block nodes must implement.
type BlockNode interface {
	Node
	blockNode()
}

// BlockSlice is a slice of BlockNodes.
type BlockSlice []BlockNode

// FirstParagraphInlines returns the inline list of the first paragraph that
// contains a inline list.
func (bns BlockSlice) FirstParagraphInlines() *InlineListNode {
	if len(bns) > 0 {
		for _, bn := range bns {
			pn, ok := bn.(*ParaNode)
			if !ok {
				continue
			}
			inl := pn.Inlines
			if inl != nil && len(inl.List) > 0 {
				return inl
			}
		}
	}
	return nil
}

// ItemNode is a node that can occur as a list item.
type ItemNode interface {
	BlockNode
	itemNode()
}

// ItemSlice is a slice of ItemNodes.
type ItemSlice []ItemNode

// ItemListNode is a list of BlockNodes.
type ItemListNode struct {
	List []ItemNode
}

// WalkChildren walks down to the descriptions.
func (iln *ItemListNode) WalkChildren(v Visitor) {
	for _, bn := range iln.List {
		Walk(v, bn)
	}
}

// DescriptionNode is a node that contains just textual description.
type DescriptionNode interface {
	ItemNode
	descriptionNode()
}

//-----------------------------------------------------------------------------
// Copyright (c) 2020-2022 Detlef Stern
//
// This file is part of Zettelstore.
//
// Zettelstore is licensed under the latest version of the EUPL (European Union
// Public License). Please see file LICENSE.txt for your rights and obligations
// under this license.
//-----------------------------------------------------------------------------

package ast

import "strings"

// Attributes store additional information about some node types.
type Attributes struct {
	Attrs map[string]string
}

// IsEmpty returns true if there are no attributes.
func (a *Attributes) IsEmpty() bool { return a == nil || len(a.Attrs) == 0 }

// HasDefault returns true, if the default attribute "-" has been set.
func (a *Attributes) HasDefault() bool {
	if a != nil {
		_, ok := a.Attrs["-"]
		return ok
	}
	return false
}

// RemoveDefault removes the default attribute
func (a *Attributes) RemoveDefault() {
	a.Remove("-")
}

// Get returns the attribute value of the given key and a succes value.
func (a *Attributes) Get(key string) (string, bool) {
	if a != nil {
		value, ok := a.Attrs[key]
		return value, ok
	}
	return "", false
}

// Clone returns a duplicate of the attribute.
func (a *Attributes) Clone() *Attributes {
	if a == nil {
		return nil
	}
	attrs := make(map[string]string, len(a.Attrs))
	for k, v := range a.Attrs {
		attrs[k] = v
	}
	return &Attributes{attrs}
}

// Set changes the attribute that a given key has now a given value.
func (a *Attributes) Set(key, value string) *Attributes {
	if a == nil {
		return &Attributes{map[string]string{key: value}}
	}
	if a.Attrs == nil {
		a.Attrs = make(map[string]string)
	}
	a.Attrs[key] = value
	return a
}

// Remove the key from the attributes.
func (a *Attributes) Remove(key string) *Attributes {
	if a != nil {
		delete(a.Attrs, key)
	}
	return a
}

// AddClass adds a value to the class attribute.
func (a *Attributes) AddClass(class string) *Attributes {
	if a == nil {
		return &Attributes{map[string]string{"class": class}}
	}
	if a.Attrs == nil {
		a.Attrs = make(map[string]string)
	}
	classes := a.GetClasses()
	for _, cls := range classes {
		if cls == class {
			return a
		}
	}
	classes = append(classes, class)
	a.Attrs["class"] = strings.Join(classes, " ")
	return a
}

// GetClasses returns the class values as a string slice
func (a *Attributes) GetClasses() []string {
	if a == nil {
		return nil
	}
	classes, ok := a.Attrs["class"]
	if !ok {
		return nil
	}
	return strings.Fields(classes)
}

//-----------------------------------------------------------------------------
// Copyright (c) 2020-2021 Detlef Stern
//
// This file is part of zettelstore.
//
// Zettelstore is licensed under the latest version of the EUPL (European Union
// Public License). Please see file LICENSE.txt for your rights and obligations
// under this license.
//-----------------------------------------------------------------------------

package ast_test

import (
	"testing"

	"zettelstore.de/z/ast"
)

func TestHasDefault(t *testing.T) {
	t.Parallel()
	attr := &ast.Attributes{}
	if attr.HasDefault() {
		t.Error("Should not have default attr")
	}
	attr = &ast.Attributes{Attrs: map[string]string{"-": "value"}}
	if !attr.HasDefault() {
		t.Error("Should have default attr")
	}
}

func TestAttrClone(t *testing.T) {
	t.Parallel()
	orig := &ast.Attributes{}
	clone := orig.Clone()
	if len(clone.Attrs) > 0 {
		t.Error("Attrs must be empty")
	}

	orig = &ast.Attributes{Attrs: map[string]string{"": "0", "-": "1", "a": "b"}}
	clone = orig.Clone()
	m := clone.Attrs
	if m[""] != "0" || m["-"] != "1" || m["a"] != "b" || len(m) != len(orig.Attrs) {
		t.Error("Wrong cloned map")
	}
	m["a"] = "c"
	if orig.Attrs["a"] != "b" {
		t.Error("Aliased map")
	}
}

//-----------------------------------------------------------------------------
// Copyright (c) 2020-2022 Detlef Stern
//
// This file is part of Zettelstore.
//
// Zettelstore is licensed under the latest version of the EUPL (European Union
// Public License). Please see file LICENSE.txt for your rights and obligations
// under this license.
//-----------------------------------------------------------------------------

package ast

import "zettelstore.de/c/zjson"

// Definition of Block nodes.

// BlockSlice is a slice of BlockNodes.
type BlockSlice []BlockNode

func (*BlockSlice) blockNode() { /* Just a marker */ }
// BlockListNode is a list of BlockNodes.
type BlockListNode struct {
	List BlockSlice
}

func (*BlockListNode) blockNode() { /* Just a marker */ }

// CreateBlockListNode make a new block list node from nodes
func CreateBlockListNode(nodes ...BlockNode) *BlockListNode {
	return &BlockListNode{List: nodes}
}

// WalkChildren walks down to the descriptions.
func (bs *BlockSlice) WalkChildren(v Visitor) {
	if bs != nil {
		for _, bn := range *bs {
func (bln *BlockListNode) WalkChildren(v Visitor) {
	if bns := bln.List; bns != nil {
		for _, bn := range bns {
			Walk(v, bn)
		}
	}
}

// FirstParagraphInlines returns the inline list of the first paragraph that
// contains a inline list.
func (bs BlockSlice) FirstParagraphInlines() InlineSlice {
	for _, bn := range bs {
		pn, ok := bn.(*ParaNode)
		if !ok {
			continue
		}
		if inl := pn.Inlines; len(inl) > 0 {
			return inl
		}
	}
	return nil
}

//--------------------------------------------------------------------------

// ParaNode contains just a sequence of inline elements.
// Another name is "paragraph".
type ParaNode struct {
	Inlines InlineSlice
	Inlines *InlineListNode
}

func (*ParaNode) blockNode()       { /* Just a marker */ }
func (*ParaNode) itemNode()        { /* Just a marker */ }
func (*ParaNode) descriptionNode() { /* Just a marker */ }

// NewParaNode creates an empty ParaNode.
func NewParaNode() *ParaNode { return &ParaNode{} }
func NewParaNode() *ParaNode { return &ParaNode{Inlines: &InlineListNode{}} }

// CreateParaNode creates a parameter block from inline nodes.
func CreateParaNode(nodes ...InlineNode) *ParaNode {
	return &ParaNode{Inlines: nodes}
	return &ParaNode{Inlines: CreateInlineListNode(nodes...)}
}

// WalkChildren walks down the inline elements.
func (pn *ParaNode) WalkChildren(v Visitor) {
	if iln := pn.Inlines; iln != nil {
	Walk(v, &pn.Inlines)
		Walk(v, iln)
	}
}

//--------------------------------------------------------------------------

// VerbatimNode contains uninterpreted text
type VerbatimNode struct {
	Kind    VerbatimKind
	Attrs   zjson.Attributes
	Attrs   *Attributes
	Content []byte
}

// VerbatimKind specifies the format that is applied to code inline nodes.
type VerbatimKind uint8

// Constants for VerbatimCode

func (*VerbatimNode) WalkChildren(Visitor) { /* No children*/ }

//--------------------------------------------------------------------------

// RegionNode encapsulates a region of block nodes.
type RegionNode struct {
	Kind    RegionKind
	Attrs   zjson.Attributes
	Blocks  BlockSlice
	Inlines InlineSlice // Optional text at the end of the region
	Attrs   *Attributes
	Blocks  *BlockListNode
	Inlines *InlineListNode // Optional text at the end of the region
}

// RegionKind specifies the actual region type.
type RegionKind uint8

// Values for RegionCode
const (
	_           RegionKind = iota
	RegionSpan             // Just a span of blocks
	RegionQuote            // A longer quotation
	RegionVerse            // Line breaks matter
)

func (*RegionNode) blockNode() { /* Just a marker */ }
func (*RegionNode) itemNode()  { /* Just a marker */ }

// WalkChildren walks down the blocks and the text.
func (rn *RegionNode) WalkChildren(v Visitor) {
	Walk(v, &rn.Blocks)
	Walk(v, &rn.Inlines)
	Walk(v, rn.Blocks)
	if iln := rn.Inlines; iln != nil {
		Walk(v, iln)
	}
}

//--------------------------------------------------------------------------

// HeadingNode stores the heading text and level.
type HeadingNode struct {
	Level    int
	Inlines  InlineSlice // Heading text, possibly formatted
	Slug     string      // Heading text, normalized
	Fragment string      // Heading text, suitable to be used as an unique URL fragment
	Attrs    zjson.Attributes
	Inlines  *InlineListNode // Heading text, possibly formatted
	Slug     string          // Heading text, normalized
	Fragment string          // Heading text, suitable to be used as an unique URL fragment
	Attrs    *Attributes
}

func (*HeadingNode) blockNode() { /* Just a marker */ }
func (*HeadingNode) itemNode()  { /* Just a marker */ }

// WalkChildren walks the heading text.
func (hn *HeadingNode) WalkChildren(v Visitor) {
	if iln := hn.Inlines; iln != nil {
	Walk(v, &hn.Inlines)
		Walk(v, iln)
	}
}

//--------------------------------------------------------------------------

// HRuleNode specifies a horizontal rule.
type HRuleNode struct {
	Attrs zjson.Attributes
	Attrs *Attributes
}

func (*HRuleNode) blockNode() { /* Just a marker */ }
func (*HRuleNode) itemNode()  { /* Just a marker */ }

// WalkChildren does nothing.
func (*HRuleNode) WalkChildren(Visitor) { /* No children*/ }

//--------------------------------------------------------------------------

// NestedListNode specifies a nestable list, either ordered or unordered.
type NestedListNode struct {
	Kind  NestedListKind
	Items []ItemSlice
	Attrs zjson.Attributes
	Attrs *Attributes
}

// NestedListKind specifies the actual list type.
type NestedListKind uint8

// Values for ListCode
const (

// DescriptionListNode specifies a description list.
type DescriptionListNode struct {
	Descriptions []Description
}

// Description is one element of a description list.
type Description struct {
	Term         InlineSlice
	Term         *InlineListNode
	Descriptions []DescriptionSlice
}

func (*DescriptionListNode) blockNode() { /* Just a marker */ }

// WalkChildren walks down to the descriptions.
func (dn *DescriptionListNode) WalkChildren(v Visitor) {
	if descrs := dn.Descriptions; descrs != nil {
		for i, desc := range descrs {
			if len(desc.Term) > 0 {
				Walk(v, &descrs[i].Term) // Otherwise, changes in desc.Term will not go back into AST
		for _, desc := range descrs {
			if term := desc.Term; term != nil {
				Walk(v, term)
			}
			if dss := desc.Descriptions; dss != nil {
				for _, dns := range dss {
					WalkDescriptionSlice(v, dns)
				}
			}
		}

	Header TableRow    // The header row
	Align  []Alignment // Default column alignment
	Rows   []TableRow  // The slice of cell rows
}

// TableCell contains the data for one table cell
type TableCell struct {
	Align   Alignment   // Cell alignment
	Inlines InlineSlice // Cell content
	Align   Alignment       // Cell alignment
	Inlines *InlineListNode // Cell content
}

// TableRow is a slice of cells.
type TableRow []*TableCell

// Alignment specifies text alignment.
// Currently only for tables.

)

func (*TableNode) blockNode() { /* Just a marker */ }

// WalkChildren walks down to the cells.
func (tn *TableNode) WalkChildren(v Visitor) {
	if header := tn.Header; header != nil {
		for i := range header {
			Walk(v, &header[i].Inlines) // Otherwise changes will not go back
		for _, cell := range header {
			if iln := cell.Inlines; iln != nil {
				Walk(v, iln)
			}
		}
	}
	if rows := tn.Rows; rows != nil {
		for _, row := range rows {
			for i := range row {
				Walk(v, &row[i].Inlines) // Otherwise changes will not go back
			for _, cell := range row {
				if iln := cell.Inlines; iln != nil {
					Walk(v, iln)
				}
			}
		}
	}
}

//--------------------------------------------------------------------------

//-----------------------------------------------------------------------------
// Copyright (c) 2020-2022 Detlef Stern
//
// This file is part of Zettelstore.
//
// Zettelstore is licensed under the latest version of the EUPL (European Union
// Public License). Please see file LICENSE.txt for your rights and obligations
// under this license.
//-----------------------------------------------------------------------------

package ast

// Definitions of inline nodes.
import (
	"unicode/utf8"


// InlineListNode is a list of BlockNodes.
type InlineListNode struct {
	List []InlineNode
}
	"zettelstore.de/c/zjson"
)


func (*InlineListNode) inlineNode() { /* Just a marker */ }
// Definitions of inline nodes.

// InlineSlice is a list of BlockNodes.
type InlineSlice []InlineNode

// CreateInlineListNode make a new inline list node from nodes
func CreateInlineListNode(nodes ...InlineNode) *InlineListNode {
	return &InlineListNode{List: nodes}
}
func (*InlineSlice) inlineNode() { /* Just a marker */ }

// CreateInlineSliceFromWords makes a new inline list from words,
// CreateInlineListNodeFromWords makes a new inline list from words,
// that will be space-separated.
func CreateInlineSliceFromWords(words ...string) InlineSlice {
	inl := make(InlineSlice, 0, 2*len(words)-1)
func CreateInlineListNodeFromWords(words ...string) *InlineListNode {
	inl := make([]InlineNode, 0, 2*len(words)-1)
	for i, word := range words {
		if i > 0 {
			inl = append(inl, &SpaceNode{Lexeme: " "})
		}
		inl = append(inl, &TextNode{Text: word})
	}
	return inl
	return &InlineListNode{List: inl}
}

// WalkChildren walks down to the list.
func (is *InlineSlice) WalkChildren(v Visitor) {
	for _, in := range *is {
		Walk(v, in)
	}
}
func (iln *InlineListNode) WalkChildren(v Visitor) {
	if ins := iln.List; ins != nil {
		for _, bn := range ins {
			Walk(v, bn)
		}
	}
}

// IsEmpty returns true if the list has no elements.
func (iln *InlineListNode) IsEmpty() bool { return iln == nil || len(iln.List) == 0 }

// Append inline node(s) to the list.
func (iln *InlineListNode) Append(in ...InlineNode) {
	iln.List = append(iln.List, in...)
}

// --------------------------------------------------------------------------

// TextNode just contains some text.
type TextNode struct {
	Text string // The text itself.
}

}

func (*SpaceNode) inlineNode() { /* Just a marker */ }

// WalkChildren does nothing.
func (*SpaceNode) WalkChildren(Visitor) { /* No children*/ }

// Count returns the number of space runes.
func (sn *SpaceNode) Count() int {
	return utf8.RuneCountInString(sn.Lexeme)
}

// --------------------------------------------------------------------------

// BreakNode signals a new line that must / should be interpreted as a new line break.
type BreakNode struct {
	Hard bool // Hard line break?
}

func (*BreakNode) inlineNode() { /* Just a marker */ }

// WalkChildren does nothing.
func (*BreakNode) WalkChildren(Visitor) { /* No children*/ }

// --------------------------------------------------------------------------

// LinkNode contains the specified link.
type LinkNode struct {
	Ref     *Reference
	Inlines InlineSlice      // The text associated with the link.
	Attrs   zjson.Attributes // Optional attributes
	Inlines *InlineListNode // The text associated with the link.
	OnlyRef bool            // True if no text was specified.
	Attrs   *Attributes     // Optional attributes
}

func (*LinkNode) inlineNode() { /* Just a marker */ }

// WalkChildren walks to the link text.
func (ln *LinkNode) WalkChildren(v Visitor) {
	if len(ln.Inlines) > 0 {
		Walk(v, &ln.Inlines)
	if iln := ln.Inlines; iln != nil {
		Walk(v, iln)
	}
}

// --------------------------------------------------------------------------

// EmbedRefNode contains the specified embedded reference material.
type EmbedRefNode struct {
	Ref     *Reference       // The reference to be embedded.
	Inlines InlineSlice      // Optional text associated with the image.
	Attrs   zjson.Attributes // Optional attributes
	Ref     *Reference      // The reference to be embedded.
	Inlines *InlineListNode // Optional text associated with the image.
	Attrs   *Attributes     // Optional attributes
	Syntax  string           // Syntax of referenced material, if known
}

func (*EmbedRefNode) inlineNode()      { /* Just a marker */ }
func (*EmbedRefNode) inlineEmbedNode() { /* Just a marker */ }

// WalkChildren walks to the text that describes the embedded material.
func (en *EmbedRefNode) WalkChildren(v Visitor) {
	if iln := en.Inlines; iln != nil {
	Walk(v, &en.Inlines)
		Walk(v, iln)
	}
}

// --------------------------------------------------------------------------

// EmbedBLOBNode contains the specified embedded BLOB material.
type EmbedBLOBNode struct {
	Blob    []byte           // BLOB data itself.
	Syntax  string           // Syntax of Blob
	Inlines InlineSlice      // Optional text associated with the image.
	Attrs   zjson.Attributes // Optional attributes
	Blob    []byte          // BLOB data itself.
	Syntax  string          // Syntax of Blob
	Inlines *InlineListNode // Optional text associated with the image.
	Attrs   *Attributes     // Optional attributes
}

func (*EmbedBLOBNode) inlineNode()      { /* Just a marker */ }
func (*EmbedBLOBNode) inlineEmbedNode() { /* Just a marker */ }

// WalkChildren walks to the text that describes the embedded material.
func (en *EmbedBLOBNode) WalkChildren(v Visitor) {
	if iln := en.Inlines; iln != nil {
	Walk(v, &en.Inlines)
		Walk(v, iln)
	}
}

// --------------------------------------------------------------------------

// CiteNode contains the specified citation.
type CiteNode struct {
	Key     string           // The citation key
	Inlines InlineSlice      // Optional text associated with the citation.
	Attrs   zjson.Attributes // Optional attributes
	Key     string          // The citation key
	Inlines *InlineListNode // Optional text associated with the citation.
	Attrs   *Attributes     // Optional attributes
}

func (*CiteNode) inlineNode() { /* Just a marker */ }

// WalkChildren walks to the cite text.
func (cn *CiteNode) WalkChildren(v Visitor) {
	if iln := cn.Inlines; iln != nil {
	Walk(v, &cn.Inlines)
		Walk(v, iln)
	}
}

// --------------------------------------------------------------------------

// MarkNode contains the specified merked position.
// It is a BlockNode too, because although it is typically parsed during inline
// mode, it is moved into block mode afterwards.
type MarkNode struct {
	Mark     string      // The mark text itself
	Slug     string      // Slugified form of Mark
	Fragment string      // Unique form of Slug
	Text     string
	Slug     string // Slugified form of Text
	Fragment string // Unique form of Slug
	Inlines  InlineSlice // Marked inline content
}

func (*MarkNode) inlineNode() { /* Just a marker */ }

// WalkChildren does nothing.
func (mn *MarkNode) WalkChildren(v Visitor) {
func (*MarkNode) WalkChildren(Visitor) { /* No children*/ }
	if len(mn.Inlines) > 0 {
		Walk(v, &mn.Inlines)
	}
}

// --------------------------------------------------------------------------

// FootnoteNode contains the specified footnote.
type FootnoteNode struct {
	Inlines InlineSlice      // The footnote text.
	Attrs   zjson.Attributes // Optional attributes
	Inlines *InlineListNode // The footnote text.
	Attrs   *Attributes     // Optional attributes
}

func (*FootnoteNode) inlineNode() { /* Just a marker */ }

// WalkChildren walks to the footnote text.
func (fn *FootnoteNode) WalkChildren(v Visitor) {
	if iln := fn.Inlines; iln != nil {
	Walk(v, &fn.Inlines)
		Walk(v, iln)
	}
}

// --------------------------------------------------------------------------

// FormatNode specifies some inline formatting.
type FormatNode struct {
	Kind    FormatKind
	Attrs   zjson.Attributes // Optional attributes.
	Inlines InlineSlice
	Attrs   *Attributes // Optional attributes.
	Inlines *InlineListNode
}

// FormatKind specifies the format that is applied to the inline nodes.
type FormatKind uint8

// Constants for FormatCode
const (
	_            FormatKind = iota
	FormatEmph              // Emphasized text.
	FormatStrong            // Strongly emphasized text.
	FormatInsert            // Inserted text.
	FormatDelete            // Deleted text.
	FormatSuper             // Superscripted text.
	FormatSub               // SubscriptedText.
	FormatQuote             // Quoted text.
	FormatSpan              // Generic inline container.
	_               FormatKind = iota
	FormatEmph                 // Emphasized text.
	FormatStrong               // Strongly emphasized text.
	FormatInsert               // Inserted text.
	FormatDelete               // Deleted text.
	FormatSuper                // Superscripted text.
	FormatSub                  // SubscriptedText.
	FormatQuote                // Quoted text.
	FormatQuotation            // Quotation text.
	FormatSpan                 // Generic inline container.
	FormatMonospace            // Monospaced text.
)

func (*FormatNode) inlineNode() { /* Just a marker */ }

// WalkChildren walks to the formatted text.
func (fn *FormatNode) WalkChildren(v Visitor) {
	if iln := fn.Inlines; iln != nil {
	Walk(v, &fn.Inlines)
		Walk(v, iln)
	}
}

// --------------------------------------------------------------------------

// LiteralNode specifies some uninterpreted text.
type LiteralNode struct {
	Kind    LiteralKind
	Attrs   zjson.Attributes // Optional attributes.
	Attrs   *Attributes // Optional attributes.
	Content []byte
}

// LiteralKind specifies the format that is applied to code inline nodes.
type LiteralKind uint8

// Constants for LiteralCode
const (
	_              LiteralKind = iota
	LiteralZettel              // Zettel content
	LiteralProg                // Inline program code
	LiteralInput               // Computer input, e.g. Keyboard strokes
	LiteralOutput              // Computer output
	LiteralKeyb                // Keyboard strokes
	LiteralOutput              // Sample output.
	LiteralComment             // Inline comment
	LiteralHTML                // Inline HTML, e.g. for Markdown
)

func (*LiteralNode) inlineNode() { /* Just a marker */ }

// WalkChildren does nothing.
func (*LiteralNode) WalkChildren(Visitor) { /* No children*/ }

//-----------------------------------------------------------------------------

package ast_test

import (
	"testing"

	"zettelstore.de/c/zjson"
	"zettelstore.de/z/ast"
)

func BenchmarkWalk(b *testing.B) {
	root := ast.BlockSlice{
	root := ast.CreateBlockListNode(
		&ast.HeadingNode{
			Inlines: ast.CreateInlineSliceFromWords("A", "Simple", "Heading"),
			Inlines: ast.CreateInlineListNodeFromWords("A", "Simple", "Heading"),
		},
		&ast.ParaNode{
			Inlines: ast.CreateInlineSliceFromWords("This", "is", "the", "introduction."),
			Inlines: ast.CreateInlineListNodeFromWords("This", "is", "the", "introduction."),
		},
		&ast.NestedListNode{
			Kind: ast.NestedListUnordered,
			Items: []ast.ItemSlice{
				[]ast.ItemNode{
					&ast.ParaNode{
						Inlines: ast.CreateInlineSliceFromWords("Item", "1"),
						Inlines: ast.CreateInlineListNodeFromWords("Item", "1"),
					},
				},
				[]ast.ItemNode{
					&ast.ParaNode{
						Inlines: ast.CreateInlineSliceFromWords("Item", "2"),
						Inlines: ast.CreateInlineListNodeFromWords("Item", "2"),
					},
				},
			},
		},
		&ast.ParaNode{
			Inlines: ast.CreateInlineSliceFromWords("This", "is", "some", "intermediate", "text."),
			Inlines: ast.CreateInlineListNodeFromWords("This", "is", "some", "intermediate", "text."),
		},
		ast.CreateParaNode(
			&ast.FormatNode{
				Kind: ast.FormatEmph,
				Attrs: &ast.Attributes{
				Attrs: zjson.Attributes(map[string]string{
					"":      "class",
					"color": "green",
				}),
				Inlines: ast.CreateInlineSliceFromWords("This", "is", "some", "emphasized", "text."),
					Attrs: map[string]string{
						"":      "class",
						"color": "green",
					},
				},
				Inlines: ast.CreateInlineListNodeFromWords("This", "is", "some", "emphasized", "text."),
			},
			&ast.SpaceNode{Lexeme: " "},
			&ast.LinkNode{
				Ref: &ast.Reference{
				Ref:     &ast.Reference{Value: "http://zettelstore.de"},
				Inlines: ast.CreateInlineSliceFromWords("URL", "text."),
					Value: "http://zettelstore.de",
				},
				Inlines: ast.CreateInlineListNodeFromWords("URL", "text."),
				OnlyRef: false,
			},
		),
	}
	)
	v := benchVisitor{}
	b.ResetTimer()
	for n := 0; n < b.N; n++ {
		ast.Walk(&v, &root)
		ast.Walk(&v, root)
	}
}

type benchVisitor struct{}

func (bv *benchVisitor) Visit(ast.Node) ast.Visitor { return bv }

//-----------------------------------------------------------------------------
// Copyright (c) 2020-2022 Detlef Stern
// Copyright (c) 2020-2021 Detlef Stern
//
// This file is part of Zettelstore.
// This file is part of zettelstore.
//
// Zettelstore is licensed under the latest version of the EUPL (European Union
// Public License). Please see file LICENSE.txt for your rights and obligations
// under this license.
//-----------------------------------------------------------------------------

// Package box provides a generic interface to zettel boxes.
package box

import (
	"context"
	"errors"
	"fmt"
	"io"
	"net/url"
	"strconv"
	"time"

	"zettelstore.de/c/api"
	"zettelstore.de/z/domain"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/search"

// ErrNotFound is returned if a zettel was not found in the box.
var ErrNotFound = errors.New("zettel not found")

// ErrConflict is returned if a box operation detected a conflict..
// One example: if calculating a new zettel identifier takes too long.
var ErrConflict = errors.New("conflict")

// ErrCapacity is returned if a box has reached its capacity.
var ErrCapacity = errors.New("capacity exceeded")

// ErrInvalidID is returned if the zettel id is not appropriate for the box operation.
type ErrInvalidID struct{ Zid id.Zid }

func (err *ErrInvalidID) Error() string { return "invalid Zettel id: " + err.Zid.String() }

// GetQueryBool is a helper function to extract bool values from a box URI.
func GetQueryBool(u *url.URL, key string) bool {
	_, ok := u.Query()[key]
	return ok
}

// GetQueryInt is a helper function to extract int values of a specified range from a box URI.
func GetQueryInt(u *url.URL, key string, min, def, max int) int {
	sVal := u.Query().Get(key)
	if sVal == "" {
		return def
	}
	iVal, err := strconv.Atoi(sVal)
	if err != nil {
		return def
	}
	if iVal < min {
		return min
	}
	if iVal > max {
		return max
	}
	return iVal
}

//-----------------------------------------------------------------------------
// Copyright (c) 2020-2022 Detlef Stern
// Copyright (c) 2020-2021 Detlef Stern
//
// This file is part of Zettelstore.
// This file is part of zettelstore.
//
// Zettelstore is licensed under the latest version of the EUPL (European Union
// Public License). Please see file LICENSE.txt for your rights and obligations
// under this license.
//-----------------------------------------------------------------------------

// Package compbox provides zettel that have computed content.

func (cb *compBox) ReadStats(st *box.ManagedBoxStats) {
	st.ReadOnly = true
	st.Zettel = len(myZettel)
	cb.log.Trace().Int("zettel", int64(st.Zettel)).Msg("ReadStats")
}

func updateMeta(m *meta.Meta) {
	m.Set(api.KeyNoIndex, api.ValueTrue)
	if _, ok := m.Get(api.KeySyntax); !ok {
		m.Set(api.KeySyntax, api.ValueSyntaxZmk)
	}
	m.Set(api.KeyRole, api.ValueRoleConfiguration)
	m.Set(api.KeyLang, api.ValueLangEN)
	m.Set(api.KeyReadOnly, api.ValueTrue)
	if _, ok := m.Get(api.KeyVisibility); !ok {
		m.Set(api.KeyVisibility, api.ValueVisibilityExpert)
	}
}

    float:left;
    display: block;
    text-align: center;
    padding:.41rem .5rem;
    text-decoration: none;
    color:black;
  }
  nav.zs-menu > a:hover, .zs-dropdown:hover button { background-color: hsl(210, 28%, 80%) }
  nav.zs-menu form { float: right }
  nav.zs-menu > a:hover, .zs-dropdown:hover button {
    background-color: hsl(210, 28%, 80%);
  }
  nav.zs-menu form {
    float: right;
  }
  nav.zs-menu form input[type=text] {
    padding: .12rem;
    border: none;
    margin-top: .25rem;
    margin-right: .5rem;
  }
  .zs-dropdown {

    float: none;
    color: black;
    padding:.41rem .5rem;
    text-decoration: none;
    display: block;
    text-align: left;
  }
  .zs-dropdown-content > a:hover { background-color: hsl(210, 28%, 75%) }
  .zs-dropdown:hover > .zs-dropdown-content { display: block }
  main { padding: 0 1rem }
  article > * + * { margin-top: .5rem }
  .zs-dropdown-content > a:hover {
    background-color: hsl(210, 28%, 75%);
  }
  .zs-dropdown:hover > .zs-dropdown-content {
    display: block;
  }
  main {
    padding: 0 1rem;
  }
  article > * + * {
    margin-top: .5rem;
  }
  article header {
    padding: 0;
    margin: 0;
  }
  h1,h2,h3,h4,h5,h6 { font-family:sans-serif; font-weight:normal }
  h1 { font-size:1.5rem;  margin:.65rem 0 }
  h2 { font-size:1.25rem; margin:.70rem 0 }
  h3 { font-size:1.15rem; margin:.75rem 0 }
  h4 { font-size:1.05rem; margin:.8rem 0; font-weight: bold }
  h5 { font-size:1.05rem; margin:.8rem 0 }
  h6 { font-size:1.05rem; margin:.8rem 0; font-weight: lighter }
  p {
  p { margin: .5rem 0 0 0 }
  ol,ul { padding-left: 1.1rem }
  li,figure,figcaption,dl { margin: 0 }
  dt { margin: .5rem 0 0 0 }
  dt+dd { margin-top: 0 }
  dd { margin: .5rem 0 0 2rem }
  dd > p:first-child { margin: 0 0 0 0 }
    margin: .5rem 0 0 0;
  }
  ol,ul {
    padding-left: 1.1rem;
  }
  li,figure,figcaption,dl {
    margin: 0;
  }
  dt {
    margin: .5rem 0 0 0;
  }
  dt+dd {
    margin-top: 0;
  }
  dd {
    margin: .5rem 0 0 2rem;
  }
  dd > p:first-child {
    margin: 0 0 0 0;
  }
  blockquote {
    border-left: 0.5rem solid lightgray;
    padding-left: 1rem;
    margin-left: 1rem;
    margin-right: 2rem;
    font-style: italic;
  }
  blockquote p { margin-bottom: .5rem }
  blockquote cite { font-style: normal }
  blockquote p {
    margin-bottom: .5rem;
  }
  blockquote cite {
    font-style: normal;
  }
  table {
    border-collapse: collapse;
    border-spacing: 0;
    max-width: 100%;
  }
  th,td {
    text-align: left;
    padding: .25rem .5rem;
  }
  td { border-bottom: 1px solid hsl(0, 0%, 85%) }
  thead th { border-bottom: 2px solid hsl(0, 0%, 70%) }
  tfoot th { border-top: 2px solid hsl(0, 0%, 70%) }
  td { border-bottom: 1px solid hsl(0, 0%, 85%); }
  thead th { border-bottom: 2px solid hsl(0, 0%, 70%); }
  tfoot th { border-top: 2px solid hsl(0, 0%, 70%); }
  main form {
    padding: 0 .5em;
    margin: .5em 0 0 0;
  }
  main form:after {
    content: ".";
    display: block;
    height: 0;
    clear: both;
    visibility: hidden;
  }
  main form div { margin: .5em 0 0 0 }
  input { font-family: monospace }
  input[type="submit"],button,select { font: inherit }
  main form div {
    margin: .5em 0 0 0
  }
  input {
    font-family: monospace;
  }
  input[type="submit"],button,select {
    font: inherit;
  }
  label { font-family: sans-serif; font-size:.9rem }
  label::after { content:":" }
  textarea {
    font-family: monospace;
    resize: vertical;
    width: 100%;
  }
  .zs-input {
    padding: .5em;
    display:block;
    border:none;
    border-bottom:1px solid #ccc;
    width:100%;
  }
  .zs-button {
    float:right;
    margin: .5em 0 .5em 1em;
  }
  a:not([class]) { text-decoration-skip-ink: auto }
  a.broken { text-decoration: line-through }
  img { max-width: 100% }
  a:not([class]) {
    text-decoration-skip-ink: auto;
  }
  .zs-broken {
    text-decoration: line-through;
  }
  img {
    max-width: 100%;
  img.right { float: right }
  ol.endnotes {
  }
  .zs-endnotes {
    padding-top: .5rem;
    border-top: 1px solid;
  }
  kbd { font-family:monospace }
  code,pre {
  code,pre,kbd {
    font-family: monospace;
    font-size: 85%;
  }
  code {
    padding: .1rem .2rem;
    background: #f0f0f0;
    border: 1px solid #ccc;

  }
  div.zs-indication {
    padding: .5rem .7rem;
    max-width: 100%;
    border-radius: .5rem;
    border: 1px solid black;
  }
  div.zs-indication p:first-child { margin-top: 0 }
  div.zs-indication p:first-child {
    margin-top: 0;
  }
  span.zs-indication {
    border: 1px solid black;
    border-radius: .25rem;
    padding: .1rem .2rem;
    font-size: 95%;
  }
  .zs-example { border-style: dotted !important }
  .zs-info {
    background-color: lightblue;
    padding: .5rem 1rem;
  }
  .zs-warning {
    background-color: lightyellow;
    padding: .5rem 1rem;
  }
  .zs-error {
    background-color: lightpink;
    border-style: none !important;
    font-weight: bold;
  }
  td.left,th.left { text-align:left }
  td.center,th.center { text-align:center }
  td.right,th.right { text-align:right }
  .zs-ta-left { text-align:left }
  .zs-ta-center { text-align:center }
  .zs-ta-right { text-align:right }
  .zs-monospace { font-family:monospace }
  .zs-font-size-0 { font-size:75% }
  .zs-font-size-1 { font-size:83% }
  .zs-font-size-2 { font-size:100% }
  .zs-font-size-3 { font-size:117% }
  .zs-font-size-4 { font-size:150% }
  .zs-font-size-5 { font-size:200% }
  .zs-deprecated { border-style: dashed; padding: .2rem }
  kbd {
    background: hsl(210, 5%, 100%);
    border: 1px solid hsl(210, 5%, 70%);
    border-radius: .25rem;
    padding: .1rem .2rem;
    font-size: 75%;
  }
  .zs-meta {
    font-size:.75rem;
    color:#444;
    margin-bottom:1rem;
  }
  .zs-meta a { color:#444 }
  h1+.zs-meta { margin-top:-1rem }
  nav > details { margin-top:1rem }
  .zs-meta a {
    color:#444;
  }
  h1+.zs-meta {
    margin-top:-1rem;
  }
  nav > details {
    margin-top:1rem;
  }
  details > summary {
    width: 100%;
    background-color: #eee;
    font-family:sans-serif;
  }
  details > ul {
    margin-top:0;
    padding-left:2rem;
    background-color: #eee;
  }
  footer { padding: 0 1rem }
  footer {
    padding: 0 1rem;
  }
  @media (prefers-reduced-motion: reduce) {
    * {
      animation-duration: 0.01ms !important;
      animation-iteration-count: 1 !important;
      transition-duration: 0.01ms !important;
      scroll-behavior: auto !important;
    }
  }

//-----------------------------------------------------------------------------
// Copyright (c) 2020-2022 Detlef Stern
// Copyright (c) 2020-2021 Detlef Stern
//
// This file is part of Zettelstore.
// This file is part of zettelstore.
//
// Zettelstore is licensed under the latest version of the EUPL (European Union
// Public License). Please see file LICENSE.txt for your rights and obligations
// under this license.
//-----------------------------------------------------------------------------

// Package constbox puts zettel inside the executable.

var constZettelMap = map[id.Zid]constZettel{
	id.ConfigurationZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore Runtime Configuration",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     api.ValueSyntaxNone,
			api.KeyNoIndex:    api.ValueTrue,
			api.KeyVisibility: api.ValueVisibilityOwner,
		},
		domain.NewContent(nil)},
	id.MustParse(api.ZidLicense): {
		constHeader{
			api.KeyTitle:      "Zettelstore License",
			api.KeyRole:       api.ValueRoleConfiguration,

		},
		domain.NewContent(contentDependencies)},
	id.BaseTemplateZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore Base HTML Template",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     syntaxTemplate,
			api.KeyNoIndex:    api.ValueTrue,
			api.KeyVisibility: api.ValueVisibilityExpert,
		},
		domain.NewContent(contentBaseMustache)},
	id.LoginTemplateZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore Login Form HTML Template",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     syntaxTemplate,
			api.KeyNoIndex:    api.ValueTrue,
			api.KeyVisibility: api.ValueVisibilityExpert,
		},
		domain.NewContent(contentLoginMustache)},
	id.ZettelTemplateZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore Zettel HTML Template",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     syntaxTemplate,
			api.KeyNoIndex:    api.ValueTrue,
			api.KeyVisibility: api.ValueVisibilityExpert,
		},
		domain.NewContent(contentZettelMustache)},
	id.InfoTemplateZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore Info HTML Template",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     syntaxTemplate,
			api.KeyNoIndex:    api.ValueTrue,
			api.KeyVisibility: api.ValueVisibilityExpert,
		},
		domain.NewContent(contentInfoMustache)},
	id.ContextTemplateZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore Context HTML Template",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     syntaxTemplate,
			api.KeyNoIndex:    api.ValueTrue,
			api.KeyVisibility: api.ValueVisibilityExpert,
		},
		domain.NewContent(contentContextMustache)},
	id.FormTemplateZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore Form HTML Template",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     syntaxTemplate,
			api.KeyNoIndex:    api.ValueTrue,
			api.KeyVisibility: api.ValueVisibilityExpert,
		},
		domain.NewContent(contentFormMustache)},
	id.RenameTemplateZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore Rename Form HTML Template",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     syntaxTemplate,
			api.KeyNoIndex:    api.ValueTrue,
			api.KeyVisibility: api.ValueVisibilityExpert,
		},
		domain.NewContent(contentRenameMustache)},
	id.DeleteTemplateZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore Delete HTML Template",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     syntaxTemplate,
			api.KeyNoIndex:    api.ValueTrue,
			api.KeyVisibility: api.ValueVisibilityExpert,
		},
		domain.NewContent(contentDeleteMustache)},
	id.ListTemplateZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore List Zettel HTML Template",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     syntaxTemplate,
			api.KeyNoIndex:    api.ValueTrue,
			api.KeyVisibility: api.ValueVisibilityExpert,
		},
		domain.NewContent(contentListZettelMustache)},
	id.RolesTemplateZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore List Roles HTML Template",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     syntaxTemplate,
			api.KeyNoIndex:    api.ValueTrue,
			api.KeyVisibility: api.ValueVisibilityExpert,
		},
		domain.NewContent(contentListRolesMustache)},
	id.TagsTemplateZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore List Tags HTML Template",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     syntaxTemplate,
			api.KeyNoIndex:    api.ValueTrue,
			api.KeyVisibility: api.ValueVisibilityExpert,
		},
		domain.NewContent(contentListTagsMustache)},
	id.ErrorTemplateZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore Error HTML Template",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     syntaxTemplate,
			api.KeyNoIndex:    api.ValueTrue,
			api.KeyVisibility: api.ValueVisibilityExpert,
		},
		domain.NewContent(contentErrorMustache)},
	id.MustParse(api.ZidBaseCSS): {
		constHeader{
			api.KeyTitle:      "Zettelstore Base CSS",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     "css",
			api.KeyNoIndex:    api.ValueTrue,
			api.KeyVisibility: api.ValueVisibilityPublic,
		},
		domain.NewContent(contentBaseCSS)},
	id.MustParse(api.ZidUserCSS): {
		constHeader{
			api.KeyTitle:      "Zettelstore User CSS",
			api.KeyRole:       api.ValueRoleConfiguration,

//-----------------------------------------------------------------------------
// Copyright (c) 2020-2022 Detlef Stern
//
// This file is part of Zettelstore.
// This file is part of zettelstore.
//
// Zettelstore is licensed under the latest version of the EUPL (European Union
// Public License). Please see file LICENSE.txt for your rights and obligations
// under this license.
//-----------------------------------------------------------------------------

// Package dirbox provides a directory-based zettel box.
package dirbox

import (
	"context"
	"errors"
	"net/url"
	"os"
	"path/filepath"
	"strconv"
	"sync"

	"zettelstore.de/c/api"
	"zettelstore.de/z/box"
	"zettelstore.de/z/box/manager"
	"zettelstore.de/z/box/notify"
	"zettelstore.de/z/domain"

		if _, err := os.Stat(path); errors.Is(err, os.ErrNotExist) {
			return nil, err
		}
		dp := dirBox{
			log:        log,
			number:     cdata.Number,
			location:   u.String(),
			readonly:   box.GetQueryBool(u, "readonly"),
			readonly:   getQueryBool(u, "readonly"),
			cdata:      *cdata,
			dir:        path,
			notifySpec: getDirSrvInfo(log, u.Query().Get("type")),
			fSrvs:      makePrime(uint32(box.GetQueryInt(u, "worker", 1, 7, 1499))),
			fSrvs:      makePrime(uint32(getQueryInt(u, "worker", 1, 7, 1499))),
		}
		return &dp, nil
	})
}

func makePrime(n uint32) uint32 {
	for !isPrime(n) {

func getDirPath(u *url.URL) string {
	if u.Opaque != "" {
		return filepath.Clean(u.Opaque)
	}
	return filepath.Clean(u.Path)
}

func getQueryBool(u *url.URL, key string) bool {
	_, ok := u.Query()[key]
	return ok
}

func getQueryInt(u *url.URL, key string, min, def, max int) int {
	sVal := u.Query().Get(key)
	if sVal == "" {
		return def
	}
	iVal, err := strconv.Atoi(sVal)
	if err != nil {
		return def
	}
	if iVal < min {
		return min
	}
	if iVal > max {
		return max
	}
	return iVal
}

// dirBox uses a directory to store zettel as files.
type dirBox struct {
	log        *logger.Logger
	number     int
	location   string
	readonly   bool

	data.refs = id.NewSet()
	data.words = store.NewWordSet()
	data.urls = store.NewWordSet()
	data.itags = store.NewWordSet()
}

func collectZettelIndexData(zn *ast.ZettelNode, data *collectData) {
	ast.Walk(data, &zn.Ast)
	ast.Walk(data, zn.Ast)
}

func collectInlineIndexData(is *ast.InlineSlice, data *collectData) {
	ast.Walk(data, is)
func collectInlineIndexData(iln *ast.InlineListNode, data *collectData) {
	ast.Walk(data, iln)
}

func (data *collectData) Visit(node ast.Node) ast.Visitor {
	switch n := node.(type) {
	case *ast.VerbatimNode:
		data.addText(string(n.Content))
	case *ast.TranscludeNode:

//-----------------------------------------------------------------------------
// Copyright (c) 2021-2022 Detlef Stern
//
// This file is part of Zettelstore.
// This file is part of zettelstore.
//
// Zettelstore is licensed under the latest version of the EUPL (European Union
// Public License). Please see file LICENSE.txt for your rights and obligations
// under this license.
//-----------------------------------------------------------------------------

package manager

import (
	"context"
	"fmt"
	"net/url"
	"time"

	"zettelstore.de/c/api"
	"zettelstore.de/z/box"
	"zettelstore.de/z/box/manager/store"
	"zettelstore.de/z/domain"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/kernel"
	"zettelstore.de/z/parser"

		}
		return false
	}
	return true
}

func (mgr *Manager) idxUpdateZettel(ctx context.Context, zettel domain.Zettel) {
	m := zettel.Meta
	if m.GetBool(api.KeyNoIndex) {
		// Zettel maybe in index
		toCheck := mgr.idxStore.DeleteZettel(ctx, m.Zid)
		mgr.idxCheckZettel(toCheck)
		return
	}

	var cData collectData
	cData.initialize()
	collectZettelIndexData(parser.ParseZettel(zettel, "", mgr.rtConfig), &cData)

	m := zettel.Meta
	zi := store.NewZettelIndex(m.Zid)
	mgr.idxCollectFromMeta(ctx, m, zi, &cData)
	mgr.idxProcessData(ctx, zi, &cData)
	toCheck := mgr.idxStore.UpdateReferences(ctx, zi)
	mgr.idxCheckZettel(toCheck)
}

		case meta.TypeID:
			mgr.idxUpdateValue(ctx, descr.Inverse, pair.Value, zi)
		case meta.TypeIDSet:
			for _, val := range meta.ListFromValue(pair.Value) {
				mgr.idxUpdateValue(ctx, descr.Inverse, val, zi)
			}
		case meta.TypeZettelmarkup:
			is := parser.ParseMetadata(pair.Value)
			collectInlineIndexData(&is, cData)
			collectInlineIndexData(parser.ParseMetadata(pair.Value), cData)
		case meta.TypeURL:
			if _, err := url.Parse(pair.Value); err == nil {
				cData.urls.Add(pair.Value)
			}
		default:
			for _, word := range strfun.NormalizeWords(pair.Value) {
				cData.words.Add(word)

//-----------------------------------------------------------------------------
// Copyright (c) 2020-2022 Detlef Stern
// Copyright (c) 2020-2021 Detlef Stern
//
// This file is part of Zettelstore.
// This file is part of zettelstore.
//
// Zettelstore is licensed under the latest version of the EUPL (European Union
// Public License). Please see file LICENSE.txt for your rights and obligations
// under this license.
//-----------------------------------------------------------------------------

// Package membox stores zettel volatile in main memory.

func init() {
	manager.Register(
		"mem",
		func(u *url.URL, cdata *manager.ConnectData) (box.ManagedBox, error) {
			return &memBox{
				log: kernel.Main.GetLogger(kernel.BoxService).Clone().
					Str("box", "mem").Int("boxnum", int64(cdata.Number)).Child(),
				u:         u,
				cdata:     *cdata,
				u:     u,
				cdata: *cdata,
				maxZettel: box.GetQueryInt(u, "max-zettel", 0, 127, 65535),
				maxBytes:  box.GetQueryInt(u, "max-bytes", 0, 65535, (1024*1024*1024)-1),
			}, nil
		})
}

type memBox struct {
	log       *logger.Logger
	u         *url.URL
	cdata     manager.ConnectData
	log    *logger.Logger
	u      *url.URL
	cdata  manager.ConnectData
	maxZettel int
	maxBytes  int
	mx        sync.RWMutex // Protects the following fields
	zettel    map[id.Zid]domain.Zettel
	curBytes  int
	zettel map[id.Zid]domain.Zettel
	mx     sync.RWMutex
}

func (mb *memBox) notifyChanged(reason box.UpdateReason, zid id.Zid) {
	if chci := mb.cdata.Notify; chci != nil {
		chci <- box.UpdateInfo{Reason: reason, Zid: zid}
	}
}

func (mb *memBox) Location() string {
	return mb.u.String()
}

func (mb *memBox) Start(context.Context) error {
	mb.mx.Lock()
	mb.zettel = make(map[id.Zid]domain.Zettel)
	mb.curBytes = 0
	mb.mx.Unlock()
	mb.log.Trace().Int("max-zettel", int64(mb.maxZettel)).Int("max-bytes", int64(mb.maxBytes)).Msg("Start Box")
	return nil
}

func (mb *memBox) Stop(context.Context) {
	mb.mx.Lock()
	mb.zettel = nil
	mb.mx.Unlock()
}

func (mb *memBox) CanCreateZettel(context.Context) bool {
func (*memBox) CanCreateZettel(context.Context) bool { return true }
	mb.mx.RLock()
	defer mb.mx.RUnlock()
	return len(mb.zettel) < mb.maxZettel
}

func (mb *memBox) CreateZettel(_ context.Context, zettel domain.Zettel) (id.Zid, error) {
	mb.mx.Lock()
	newBytes := mb.curBytes + zettel.Length()
	if mb.maxZettel < len(mb.zettel) || mb.maxBytes < newBytes {
		mb.mx.Unlock()
		return id.Invalid, box.ErrCapacity
	}
	zid, err := box.GetNewZid(func(zid id.Zid) (bool, error) {
		_, ok := mb.zettel[zid]
		return !ok, nil
	})
	if err != nil {
		mb.mx.Unlock()
		return id.Invalid, err
	}
	meta := zettel.Meta.Clone()
	meta.Zid = zid
	zettel.Meta = meta
	mb.zettel[zid] = zettel
	mb.curBytes = newBytes
	mb.mx.Unlock()
	mb.notifyChanged(box.OnUpdate, zid)
	mb.log.Trace().Zid(zid).Msg("CreateZettel")
	return zid, nil
}

func (mb *memBox) GetZettel(_ context.Context, zid id.Zid) (domain.Zettel, error) {

			mb.cdata.Enricher.Enrich(ctx, m, mb.cdata.Number)
			handle(m)
		}
	}
	return nil
}

func (mb *memBox) CanUpdateZettel(_ context.Context, zettel domain.Zettel) bool {
	mb.mx.RLock()
	defer mb.mx.RUnlock()
	zid := zettel.Meta.Zid
	if !zid.IsValid() {
		return false
	}

func (*memBox) CanUpdateZettel(context.Context, domain.Zettel) bool { return true }
	newBytes := mb.curBytes + zettel.Length()
	if prevZettel, found := mb.zettel[zid]; found {
		newBytes -= prevZettel.Length()
	}

	return newBytes < mb.maxBytes
}

func (mb *memBox) UpdateZettel(_ context.Context, zettel domain.Zettel) error {
	mb.mx.Lock()
	m := zettel.Meta.Clone()
	if !m.Zid.IsValid() {
		return &box.ErrInvalidID{Zid: m.Zid}
	meta := zettel.Meta.Clone()
	if !meta.Zid.IsValid() {
		return &box.ErrInvalidID{Zid: meta.Zid}
	}

	mb.mx.Lock()
	newBytes := mb.curBytes + zettel.Length()
	if prevZettel, found := mb.zettel[m.Zid]; found {
		newBytes -= prevZettel.Length()
	}
	if mb.maxBytes < newBytes {
		mb.mx.Unlock()
		return box.ErrCapacity
	}

	zettel.Meta = m
	mb.zettel[m.Zid] = zettel
	zettel.Meta = meta
	mb.zettel[meta.Zid] = zettel
	mb.curBytes = newBytes
	mb.mx.Unlock()
	mb.notifyChanged(box.OnUpdate, m.Zid)
	mb.notifyChanged(box.OnUpdate, meta.Zid)
	mb.log.Trace().Msg("UpdateZettel")
	return nil
}

func (*memBox) AllowRenameZettel(context.Context, id.Zid) bool { return true }

func (mb *memBox) RenameZettel(_ context.Context, curZid, newZid id.Zid) error {

	_, ok := mb.zettel[zid]
	mb.mx.RUnlock()
	return ok
}

func (mb *memBox) DeleteZettel(_ context.Context, zid id.Zid) error {
	mb.mx.Lock()
	oldZettel, found := mb.zettel[zid]
	if _, ok := mb.zettel[zid]; !ok {
	if !found {
		mb.mx.Unlock()
		return box.ErrNotFound
	}
	delete(mb.zettel, zid)
	mb.curBytes -= oldZettel.Length()
	mb.mx.Unlock()
	mb.notifyChanged(box.OnDelete, zid)
	mb.log.Trace().Msg("DeleteZettel")
	return nil
}

func (mb *memBox) ReadStats(st *box.ManagedBoxStats) {
	st.ReadOnly = false
	mb.mx.RLock()
	st.Zettel = len(mb.zettel)
	mb.mx.RUnlock()
	mb.log.Trace().Int("zettel", int64(st.Zettel)).Msg("ReadStats")
}

//-----------------------------------------------------------------------------
// Copyright (c) 2020-2022 Detlef Stern
// Copyright (c) 2020-2021 Detlef Stern
//
// This file is part of Zettelstore.
// This file is part of zettelstore.
//
// Zettelstore is licensed under the latest version of the EUPL (European Union
// Public License). Please see file LICENSE.txt for your rights and obligations
// under this license.
//-----------------------------------------------------------------------------

package cmd

	ucListTags := usecase.NewListTags(protectedBoxManager)
	ucZettelContext := usecase.NewZettelContext(protectedBoxManager, rtConfig)
	ucDelete := usecase.NewDeleteZettel(ucLog, protectedBoxManager)
	ucUpdate := usecase.NewUpdateZettel(ucLog, protectedBoxManager)
	ucRename := usecase.NewRenameZettel(ucLog, protectedBoxManager)
	ucUnlinkedRefs := usecase.NewUnlinkedReferences(protectedBoxManager, rtConfig)
	ucRefresh := usecase.NewRefresh(ucLog, protectedBoxManager)
	ucVersion := usecase.NewVersion(kernel.Main.GetConfig(kernel.CoreService, kernel.CoreVersion).(string))

	webSrv.Handle("/", wui.MakeGetRootHandler(protectedBoxManager))

	// Web user interface
	if !authManager.IsReadonly() {
		webSrv.AddZettelRoute('b', server.MethodGet, wui.MakeGetRenameZettelHandler(
			ucGetMeta, &ucEvaluate))
		webSrv.AddZettelRoute('b', server.MethodPost, wui.MakePostRenameZettelHandler(&ucRename))
		webSrv.AddZettelRoute('c', server.MethodGet, wui.MakeGetCreateZettelHandler(
			ucGetZettel, &ucCreateZettel))
		webSrv.AddZettelRoute('c', server.MethodGet, wui.MakeGetCopyZettelHandler(
			ucGetZettel, usecase.NewCopyZettel()))
		webSrv.AddZettelRoute('c', server.MethodPost, wui.MakePostCreateZettelHandler(&ucCreateZettel))
		webSrv.AddZettelRoute('d', server.MethodGet, wui.MakeGetDeleteZettelHandler(
			ucGetMeta, ucGetAllMeta, &ucEvaluate))
		webSrv.AddZettelRoute('d', server.MethodPost, wui.MakePostDeleteZettelHandler(&ucDelete))
		webSrv.AddZettelRoute('e', server.MethodGet, wui.MakeEditGetZettelHandler(ucGetZettel))
		webSrv.AddZettelRoute('e', server.MethodPost, wui.MakeEditSetZettelHandler(&ucUpdate))
		webSrv.AddZettelRoute('f', server.MethodGet, wui.MakeGetFolgeZettelHandler(
			ucGetZettel, usecase.NewFolgeZettel(rtConfig)))
		webSrv.AddZettelRoute('f', server.MethodPost, wui.MakePostCreateZettelHandler(&ucCreateZettel))
		webSrv.AddZettelRoute('g', server.MethodGet, wui.MakeGetNewZettelHandler(
			ucGetZettel, usecase.NewNewZettel()))
		webSrv.AddZettelRoute('g', server.MethodPost, wui.MakePostCreateZettelHandler(&ucCreateZettel))
	}
	webSrv.AddListRoute('g', server.MethodGet, wui.MakeGetGoActionHandler(&ucRefresh))
	webSrv.AddListRoute('h', server.MethodGet, wui.MakeListHTMLMetaHandler(
		ucListMeta, ucListRoles, ucListTags, &ucEvaluate))
	webSrv.AddZettelRoute('h', server.MethodGet, wui.MakeGetHTMLZettelHandler(
		&ucEvaluate, ucGetMeta))
	webSrv.AddListRoute('i', server.MethodGet, wui.MakeGetLoginOutHandler())
	webSrv.AddListRoute('i', server.MethodPost, wui.MakePostLoginHandler(&ucAuthenticate))
	webSrv.AddZettelRoute('i', server.MethodGet, wui.MakeGetInfoHandler(
		ucParseZettel, &ucEvaluate, ucGetMeta, ucGetAllMeta, ucUnlinkedRefs))
	webSrv.AddZettelRoute('k', server.MethodGet, wui.MakeZettelContextHandler(
		ucZettelContext, &ucEvaluate))

	// API
	webSrv.AddListRoute('a', server.MethodPost, a.MakePostLoginHandler(&ucAuthenticate))
	webSrv.AddListRoute('a', server.MethodPut, a.MakeRenewAuthHandler())
	webSrv.AddListRoute('j', server.MethodGet, a.MakeListMetaHandler(ucListMeta))
	webSrv.AddZettelRoute('j', server.MethodGet, a.MakeGetZettelHandler(ucGetZettel))
	webSrv.AddZettelRoute('l', server.MethodGet, a.MakeGetLinksHandler(ucEvaluate))
	webSrv.AddZettelRoute('m', server.MethodGet, a.MakeGetMetaHandler(ucGetMeta))
	webSrv.AddZettelRoute('o', server.MethodGet, a.MakeGetOrderHandler(
		usecase.NewZettelOrder(protectedBoxManager, ucEvaluate)))
	webSrv.AddZettelRoute('p', server.MethodGet, a.MakeGetParsedZettelHandler(ucParseZettel))
	webSrv.AddListRoute('r', server.MethodGet, a.MakeListRoleHandler(ucListRoles))
	webSrv.AddListRoute('t', server.MethodGet, a.MakeListTagsHandler(ucListTags))
	webSrv.AddZettelRoute('u', server.MethodGet, a.MakeListUnlinkedMetaHandler(
		ucGetMeta, ucUnlinkedRefs, &ucEvaluate))
	webSrv.AddListRoute('v', server.MethodPost, a.MakePostEncodeInlinesHandler(ucEvaluate))
	webSrv.AddZettelRoute('v', server.MethodGet, a.MakeGetEvalZettelHandler(ucEvaluate))
	webSrv.AddListRoute('x', server.MethodGet, a.MakeGetDataHandler(ucVersion))
	webSrv.AddListRoute('x', server.MethodPost, a.MakePostCommandHandler(&ucIsAuth, &ucRefresh))
	webSrv.AddZettelRoute('x', server.MethodGet, a.MakeZettelContextHandler(ucZettelContext))
	webSrv.AddListRoute('z', server.MethodGet, a.MakeListPlainHandler(ucListMeta))
	webSrv.AddZettelRoute('z', server.MethodGet, a.MakeGetPlainZettelHandler(ucGetZettel))
	if !authManager.IsReadonly() {
		webSrv.AddListRoute('j', server.MethodPost, a.MakePostCreateZettelHandler(&ucCreateZettel))
		webSrv.AddZettelRoute('j', server.MethodPut, a.MakeUpdateZettelHandler(&ucUpdate))

// Mention all needed encoders, parsers and stores to have them registered.
import (
	_ "zettelstore.de/z/box/compbox"       // Allow to use computed box.
	_ "zettelstore.de/z/box/constbox"      // Allow to use global internal box.
	_ "zettelstore.de/z/box/dirbox"        // Allow to use directory box.
	_ "zettelstore.de/z/box/filebox"       // Allow to use file box.
	_ "zettelstore.de/z/box/membox"        // Allow to use in-memory box.
	_ "zettelstore.de/z/encoder/djsonenc"  // Allow to use DJSON encoder.
	_ "zettelstore.de/z/encoder/htmlenc"   // Allow to use HTML encoder.
	_ "zettelstore.de/z/encoder/nativeenc" // Allow to use native encoder.
	_ "zettelstore.de/z/encoder/textenc"   // Allow to use text encoder.
	_ "zettelstore.de/z/encoder/zjsonenc"  // Allow to use ZJSON encoder.
	_ "zettelstore.de/z/encoder/zmkenc"    // Allow to use zmk encoder.
	_ "zettelstore.de/z/kernel/impl"       // Allow kernel implementation to create itself
	_ "zettelstore.de/z/parser/blob"       // Allow to use BLOB parser.
	_ "zettelstore.de/z/parser/draw"       // Allow to use draw parser.
	_ "zettelstore.de/z/parser/markdown"   // Allow to use markdown parser.
	_ "zettelstore.de/z/parser/none"       // Allow to use none parser.
	_ "zettelstore.de/z/parser/plain"      // Allow to use plain parser.
	_ "zettelstore.de/z/parser/zettelmark" // Allow to use zettelmark parser.
)

	Embeds []*ast.Reference // list of all embedded material
	Cites  []*ast.CiteNode  // list of all referenced citations
}

// References returns all references mentioned in the given zettel. This also
// includes references to images.
func References(zn *ast.ZettelNode) (s Summary) {
	if zn.Ast != nil {
	ast.Walk(&s, &zn.Ast)
		ast.Walk(&s, zn.Ast)
	}
	return s
}

// Visit all node to collect data for the summary.
func (s *Summary) Visit(node ast.Node) ast.Visitor {
	switch n := node.(type) {
	case *ast.TranscludeNode:

	summary := collect.References(zn)
	if summary.Links != nil || summary.Embeds != nil {
		t.Error("No links/images expected, but got:", summary.Links, "and", summary.Embeds)
	}

	intNode := &ast.LinkNode{Ref: parseRef("01234567890123")}
	para := ast.CreateParaNode(intNode, &ast.LinkNode{Ref: parseRef("https://zettelstore.de/z")})
	zn.Ast = ast.BlockSlice{para}
	zn.Ast = ast.CreateBlockListNode(para)
	summary = collect.References(zn)
	if summary.Links == nil || summary.Embeds != nil {
		t.Error("Links expected, and no images, but got:", summary.Links, "and", summary.Embeds)
	}

	para.Inlines = append(para.Inlines, intNode)
	para.Inlines.Append(intNode)
	summary = collect.References(zn)
	if cnt := len(summary.Links); cnt != 3 {
		t.Error("Link count does not work. Expected: 3, got", summary.Links)
	}
}

func TestEmbed(t *testing.T) {
	t.Parallel()
	zn := &ast.ZettelNode{
		Ast: ast.CreateBlockListNode(
		Ast: ast.BlockSlice{ast.CreateParaNode(&ast.EmbedRefNode{Ref: parseRef("12345678901234")})},
			ast.CreateParaNode(&ast.EmbedRefNode{Ref: parseRef("12345678901234")}),
		),
	}
	summary := collect.References(zn)
	if summary.Embeds == nil {
		t.Error("Only image expected, but got: ", summary.Embeds)
	}
}

// Package collect provides functions to collect items from a syntax tree.
package collect

import "zettelstore.de/z/ast"

// Order of internal reference within the given zettel.
func Order(zn *ast.ZettelNode) (result []*ast.Reference) {
	if zn.Ast == nil {
		return nil
	}
	for _, bn := range zn.Ast {
	for _, bn := range zn.Ast.List {
		ln, ok := bn.(*ast.NestedListNode)
		if !ok {
			continue
		}
		switch ln.Kind {
		case ast.NestedListOrdered, ast.NestedListUnordered:
			for _, is := range ln.Items {

				return ref
			}
		}
	}
	return nil
}

func firstInlineZettelReference(is ast.InlineSlice) (result *ast.Reference) {
	for _, inl := range is {
func firstInlineZettelReference(iln *ast.InlineListNode) (result *ast.Reference) {
	if iln == nil {
		return nil
	}
	for _, inl := range iln.List {
		switch in := inl.(type) {
		case *ast.LinkNode:
			if ref := in.Ref; ref.IsZettel() {
				return ref
			}
			result = firstInlineZettelReference(in.Inlines)
		case *ast.EmbedRefNode:

id: 20210916194900
title: Checklist for Release
role: zettel
syntax: zmk
modified: 20220309105459
modified: 20211214181017

# Sync with the official repository
#* ``fossil sync -u``
# Make sure that all dependencies are up-to-date.
#* ``cat go.mod``
# Clean up your Go workspace:
#* ``go run tools/build.go clean`` (alternatively: ``make clean``).
# All internal tests must succeed:
#* ``go run tools/build.go relcheck`` (alternatively: ``make relcheck``).
# The API tests must succeed on every development platform:
#* ``go run tools/build.go testapi`` (alternatively: ``make api``).
# Run [[linkchecker|https://linkchecker.github.io/linkchecker/]] with the manual:

id: 00000000000100
title: Zettelstore Runtime Configuration
role: configuration
syntax: none
default-copyright: (c) 2020-2022 by Detlef Stern <ds@zettelstore.de>
default-license: EUPL-1.2-or-later
default-visibility: public
footer-html: <hr><p><a href="/home/doc/trunk/www/impri.wiki">Imprint / Privacy</a></p>
home-zettel: 00001000000000
modified: 20220215171041
no-index: true
site-name: Zettelstore Manual
visibility: owner

id: 00001003305000
title: Enable Zettelstore to start automatically on Windows
role: manual
tags: #installation #manual #zettelstore
syntax: zmk
modified: 20220218125541
modified: 20211125201602

Windows is a complicated beast. There are several ways to automatically start Zettelstore.

=== Startup folder

One way is to use the [[autostart folder|https://support.microsoft.com/en-us/windows/add-an-app-to-run-automatically-at-startup-in-windows-10-150da165-dcd9-7230-517b-cf3c295d89dd]].
Open the folder where you have placed in the Explorer.
Create a shortcut file for the Zettelstore executable.
There are some ways to do this:
* Execute a right-click on the executable, and choose the menu entry ""Create shortcut"",
* Execute a right-click on the executable, and then click Send To > Desktop (Create shortcut).
* Drag the executable to your Desktop with pressing the ''Alt''-Key.
* Drag the executable to your Desktop with pressing the ++Alt++-Key.

If you have created the shortcut file, you must move it into the Startup folder.
Press the Windows logo key and the key ''R'', type ''shell:startup''.
Press the Windows logo key and the key ++R++, type ''shell:startup''.
Select the OK button.
This will open the Startup folder.
Move the shortcut file into this folder.

The next time you log into your computer, Zettelstore will be started automatically.
However, it remains visible, at least in the task bar.

All you have to do is to open your web browser, enter the appropriate URL, and there you go.

On the negative side, you will not be notified when you enter the wrong data in the Task scheduler and Zettelstore fails to start.
This can be mitigated by first using the command line prompt to start Zettelstore with the appropriate options.
Once everything works, you can register Zettelstore to be automatically started by the task scheduler.
There you should make sure that you have followed the first steps as described on the [[parent page|00001003300000]].

To sart the Task scheduler management console, press the Windows logo key and the key ''R'', type ''taskschd.msc''.
To sart the Task scheduler management console, press the Windows logo key and the key ++R++, type ''taskschd.msc''.
Select the OK button.

{{00001003305102}}

This will start the ""Task Scheduler"".

Now, create a new task with ""Create Task ...""

id: 00001003315000
title: Enable Zettelstore to start automatically on Linux
role: manual
tags: #installation #manual #zettelstore
syntax: zmk
modified: 20220307104944
modified: 20220131162209

Since there is no such thing as the one Linux, there are too many different ways to automatically start Zettelstore.

* One way is to interpret your Linux desktop system as a server and use the [[recipe to install Zettelstore on a server|00001003600000]].
** See below for a lighter alternative.
* If you are using the [[Gnome Desktop|https://www.gnome.org/]], you could use the tool [[Tweak|https://wiki.gnome.org/action/show/Apps/Tweaks]] (formerly known as ""GNOME Tweak Tool"" or just ""Tweak Tool"").
  It allows to specify application that should run on startup / login.
* [[KDE|https://kde.org/]] provides a system setting to [[autostart|https://docs.kde.org/stable5/en/plasma-workspace/kcontrol/autostart/]] applications.
* [[Xfce|https://xfce.org/]] allows to specify [[autostart applications|https://docs.xfce.org/xfce/xfce4-session/preferences#application_autostart]].
* [[LXDE|https://www.lxde.org/]] uses [[LXSession Edit|https://wiki.lxde.org/en/LXSession_Edit]] to allow users to specify autostart applications.

If you use a different desktop environment, it often helps to to provide its name and the string ""autostart"" to google for it with the search engine of your choice.

Yet another way is to make use of the middleware that is provided.
Many Linux distributions make use of [[systemd|https://systemd.io/]], which allows to start processes on behalf of an user.
On the command line, adapt the following script to your own needs and execute it:
```
# mkdir -p "$HOME/.config/systemd/user"
# cd "$HOME/.config/systemd/user"
# cat <<__EOF__ > zettelstore.service
[Unit]
Description=Zettelstore
After=network.target home.mount

[Service]
ExecStart=/usr/local/bin/zettelstore run -d zettel

[Install]
WantedBy=default.target
__EOF__
# systemctl --user daemon-reload
# systemctl --user enable zettelstore.service
# systemctl --user start zettelstore.service
# systemctl --user status zettelstore.service
```
The last command should output some lines to indicate success.

id: 00001004010000
title: Zettelstore startup configuration
role: manual
tags: #configuration #manual #zettelstore
syntax: zmk
modified: 20220304115353
modified: 20211212143318

The configuration file, as specified by the ''-c CONFIGFILE'' [[command line option|00001004051000]], allows you to specify some startup options.
These options cannot be stored in a [[configuration zettel|00001004020000]] because either they are needed before Zettelstore can start or because of security reasons.
For example, Zettelstore need to know in advance, on which network address is must listen or where zettel are stored.
An attacker that is able to change the owner can do anything.
Therefore only the owner of the computer on which Zettelstore runs can change this information.

The file for startup configuration must be created via a text editor in advance.

The syntax of the configuration file is the same as for any zettel metadata.
The following keys are supported:

; [!admin-port|''admin-port'']
; [!admin-port]''admin-port''
: Specifies the TCP port through which you can reach the [[administrator console|00001004100000]].
  A value of ""0"" (the default) disables the administrator console.
  A value of ''0'' (the default) disables the administrator console.
  The administrator console will only be enabled if Zettelstore is started with the [[''run'' sub-command|00001004051000]].

  On most operating systems, the value must be greater than ""1024"" unless you start Zettelstore with the full privileges of a system administrator (which is not recommended).
  On most operating systems, the value must be greater than ''1024'' unless you start Zettelstore with the full privileges of a system administrator (which is not recommended).

  Default: ""0""
; [!box-uri-x|''box-uri-X''], where __X__ is a number greater or equal to one
  Default: ''0''
; [!box-uri-x]''box-uri-__X__'', where __X__ is a number greater or equal to one
: Specifies a [[box|00001004011200]] where zettel are stored.
  During startup __X__ is counted up, starting with one, until no key is found.
  This allows to configure more than one box.

  If no ''box-uri-1'' key is given, the overall effect will be the same as if only ''box-uri-1'' was specified with the value ""dir://.zettel"".
  If no ''box-uri-1'' key is given, the overall effect will be the same as if only ''box-uri-1'' was specified with the value ''dir://.zettel''.
  In this case, even a key ''box-uri-2'' will be ignored.
; [!debug-mode|''debug-mode'']
: Allows to debug the Zettelstore software (mostly used by the developers) if set to [[true|00001006030500]]
; [!debug-mode]''debug-mode''
: Allows to debug the Zettelstore software (mostly used by the developers).
  Disables any timeout values of the internal web server and does not send some security-related data.
  Sets [[''log-level''|#log-level]] to ""debug"".

  Do not enable it for a production server.

  Default: ""false""
; [!default-dir-box-type|''default-dir-box-type'']
  Default: ''false''
; [!default-dir-box-type]''default-dir-box-type''
: Specifies the default value for the (sub-) type of [[directory boxes|00001004011400#type]].
  Zettel are typically stored in such boxes.

  Default: ""notify""
; [!insecure-cookie|''insecure-cookie'']
: Must be set to [[true|00001006030500]], if authentication is enabled and Zettelstore is not accessible not via HTTPS (but via HTTP).
  Default: ''notify''
; [!insecure-cookie]''insecure-cookie''
: Must be set to ''true'', if authentication is enabled and Zettelstore is not accessible not via HTTPS (but via HTTP).
  Otherwise web browser are free to ignore the authentication cookie.

  Default: ""false""
; [!listen-addr|''listen-addr'']
  Default: ''false''
; [!listen-addr]''listen-addr''
: Configures the network address, where the Zettelstore service is listening for requests.
  Syntax is: ''[NETWORKIP]:PORT'', where ''NETWORKIP'' is the IP-address of the networking interface (or something like ""0.0.0.0"" if you want to listen on all network interfaces, and ''PORT'' is the TCP port.
  Syntax is: ''[NETWORKIP]:PORT'', where ''NETWORKIP'' is the IP-address of the networking interface (or something like ''0.0.0.0'' if you want to listen on all network interfaces, and ''PORT'' is the TCP port.

  Default value: ""127.0.0.1:23123""
; [!log-level|''log-level'']
  Default value: ''"127.0.0.1:23123"''
; [!log-level]''log-level''
: Specify the global [[logging level|00001004059700]] for the whole application, overwriting the level ""debug"" set by configuration [[''debug-mode''|#debug-mode]].
  Can be changed at runtime, even for specific internal services, with the ''log-level'' command of the [[administrator console|00001004101000#log-level]].
  
  Default: ""info"".
  Default: ''info''.

  When you are familiar to operate the Zettelstore, you might set the level to ""warn"" or ""error"" to receive less noisy messages from the Zettelstore.
; [!owner|''owner'']
  When you are familiar to operate the Zettelstore, you might set the level to ''warn'' or ''error'' to receive less noisy messages from the Zettelstore.
; [!owner]''owner''
: [[Identifier|00001006050000]] of a zettel that contains data about the owner of the Zettelstore.
  The owner has full authorization for the Zettelstore.
  Only if owner is set to some value, user [[authentication|00001010000000]] is enabled.
; [!persistent-cookie|''persistent-cookie'']
: A [[boolean value|00001006030500]] to make the access cookie persistent.
; [!persistent-cookie]''persistent-cookie''
: A boolean value to make the access cookie persistent.
  This is helpful if you access the Zettelstore via a mobile device.
  On these devices, the operating system is free to stop the web browser and to remove temporary cookies.
  Therefore, an authenticated user will be logged off.

  If ""true"", a persistent cookie is used.
  If ''true'', a persistent cookie is used.
  Its lifetime exceeds the lifetime of the authentication token (see option ''token-lifetime-html'') by 30 seconds.

  Default: ""false""
; [!read-only-mode|''read-only-mode'']
: Puts the Zettelstore service into a read-only mode, if set to a [[true value|00001006030500]].
  Default: ''false''
; [!read-only-mode]''read-only-mode''
: Puts the Zettelstore service into a read-only mode.
  No changes are possible.

  Default: ""false"".
; [!token-lifetime-api|''token-lifetime-api''], [!token-lifetime-html|''token-lifetime-html'']
  Default: false.
; [!token-lifetime-api]''token-lifetime-api'', [!token-lifetime-html]''token-lifetime-html''
: Define lifetime of access tokens in minutes.
  Values are only valid if authentication is enabled, i.e. key ''owner'' is set.

  ''token-lifetime-api'' is for accessing Zettelstore via its [[API|00001012000000]].
  Default: ""10"".
  Default: 10.

  ''token-lifetime-html'' specifies the lifetime for the HTML views.
  Default: 60.
  It is automatically extended, when a new HTML view is rendered.
  Default: ""60"".
; [!url-prefix|''url-prefix'']
; [!url-prefix]''url-prefix''
: Add the given string as a prefix to the local part of a Zettelstore local URL/URI when rendering zettel representations.
  Must begin and end with a slash character (""''/''"", U+002F).
  Must begin and end with a slash character (""''/''"", ''U+002F'').

  Default: ""/"".
  Default: ''"/"''.

  This allows to use a forwarding proxy [[server|00001010090100]] in front of the Zettelstore.
; [!verbose-mode|''verbose-mode'']
: Be more verbose when logging data, if set to a [[true value|00001006030500]].
; [!verbose-mode]''verbose-mode''
: Be more verbose when logging data.

  Default: ""false""
  Default: false

id: 00001004011200
title: Zettelstore boxes
role: manual
tags: #configuration #manual #zettelstore
syntax: zmk
modified: 20220307121547
modified: 20211103163225

A Zettelstore must store its zettel somehow and somewhere.
In most cases you want to store your zettel as files in a directory.
Under certain circumstances you may want to store your zettel elsewhere.

An example are the [[predefined zettel|00001005090000]] that come with a Zettelstore.
They are stored within the software itself.
In another situation you may want to store your zettel volatile, e.g. if you want to provide a sandbox for experimenting.

To cope with these (and more) situations, you configure Zettelstore to use one or more __boxes__.
This is done via the ''box-uri-X'' keys of the [[startup configuration|00001004010000#box-uri-X]] (X is a number).
Boxes are specified using special [[URIs|https://en.wikipedia.org/wiki/Uniform_Resource_Identifier]], somehow similar to web addresses.

The following box URIs are supported:

; [!dir|''dir://DIR'']
; [!dir]''dir:\//DIR''
: Specifies a directory where zettel files are stored.
  ''DIR'' is the file path.
  Although it is possible to use relative file paths, such as ''./zettel'' (→ URI is ''dir://.zettel''), it is preferable to use absolute file paths, e.g. ''/home/user/zettel''.
  Although it is possible to use relative file paths, such as ''./zettel'' (→ URI is ''dir:\//.zettel''), it is preferable to use absolute file paths, e.g. ''/home/user/zettel''.

  The directory must exist before starting the Zettelstore[^There is one exception: when Zettelstore is [[started without any parameter|00001004050000]], e.g. via double-clicking its icon, an directory called ''./zettel'' will be created.].

  It is possible to [[configure|00001004011400]] a directory box.
; [!file|''file:FILE.zip'' or ''file:///path/to/file.zip'']
; [!file]''file:FILE.zip'' oder ''file:/\//path/to/file.zip''
: Specifies a ZIP file which contains files that store zettel.
  You can create such a ZIP file, if you zip a directory full of zettel files.

  This box is always read-only.
; [!mem|''mem:'']
; [!mem]''mem:''
: Stores all its zettel in volatile memory.
  If you stop the Zettelstore, all changes are lost.
  To limit usage of volatile memory, you should [[configure|00001004011600]] this type of box, although the default values might be valid for your use case.

All boxes that you configure via the ''box-uri-X'' keys form a chain of boxes.
If a zettel should be retrieved, a search starts in the box specified with the ''box-uri-2'' key, then ''box-uri-3'' and so on.
If a zettel is created or changed, it is always stored in the box specified with the ''box-uri-1'' key.
This allows to overwrite zettel from other boxes, e.g. the predefined zettel.

If you use the ''mem:'' box, where zettel are stored in volatile memory, it makes only sense if you configure it as ''box-uri-1''.
Such a box will be empty when Zettelstore starts and only the first box will receive updates.
You must make sure that your computer has enough RAM to store all zettel.

id: 00001004011400
title: Configure file directory boxes
role: manual
tags: #configuration #manual #zettelstore
syntax: zmk
modified: 20220307121244
modified: 20211216152540

Under certain circumstances, it is preferable to further configure a file directory box.
This is done by appending query parameters after the base box URI ''dir:\//DIR''.

The following parameters are supported:

|= Parameter:|Description|Default value:|
|type|(Sub-) Type of the directory service|(value of ""[[default-dir-box-type|00001004010000#default-dir-box-type]]"")
|type|(Sub-) Type of the directory service|(value of ''[[default-dir-box-type|00001004010000#default-dir-box-type]]'')
|worker|Number of worker that can access the directory in parallel|7
|readonly|Allow only operations that do not create or change zettel|n/a

=== Type
On some operating systems, Zettelstore tries to detect changes to zettel files outside of Zettelstore's control[^This includes Linux, Windows, and macOS.].
On other operating systems, this may be not possible, due to technical limitations.
Automatic detection of external changes is also not possible, if zettel files are put on an external service, such as a file server accessed via SMD/CIFS or NFS.

id: 00001004011600
title: Configure memory boxes
role: manual
tags: #configuration #manual #zettelstore
syntax: zmk
modified: 20220307122554

Under most circumstances, it is preferable to further configure a memory box.
This is done by appending query parameters after the base box URI ''mem:''.

The following parameters are supported:

|= Parameter:|Description|Default value:|Maximum value:
|max-bytes|Maximum number of bytes the box will store|65535|1073741824 (1 GiB)
|max-zettel|Maximum number of zettel|127|65535

The default values are somehow arbitrarily, but applicable for many use cases.

While the number of zettel should be easily calculable by an user, the number of bytes might be a little more difficult.

Metadata consumes 6 bytes for the zettel identifier and for each metadata value one byte for the separator, plus the length of key and data.
Then size of the content is its size in bytes.
For text content, its the number of bytes for its UTF-8 encoding.

If one of the limits are exceeded, Zettelstore will give an error indication, based on the HTTP status code 507.

id: 00001004020000
title: Configure the running Zettelstore
role: manual
tags: #configuration #manual #zettelstore
syntax: zmk
modified: 20220304114412
modified: 20220111103757

You can configure a running Zettelstore by modifying the special zettel with the ID [[00000000000100]].
This zettel is called __configuration zettel__.
The following metadata keys change the appearance / behavior of Zettelstore:

; [!default-copyright|''default-copyright'']
; [!default-copyright]''default-copyright''
: Copyright value to be used when rendering content.
  Can be overwritten in a zettel with [[meta key|00001006020000]] ''copyright''.

  Default: (the empty string).
; [!default-lang|''default-lang'']
; [!default-lang]''default-lang''
: Default language to be used when displaying content.
  Can be overwritten in a zettel with [[meta key|00001006020000]] ''lang''. Default: ""en"".

  This value is also used to specify the language for all non-zettel content, e.g. lists or search results.

  Use values according to the language definition of [[RFC-5646|https://tools.ietf.org/html/rfc5646]].
; [!default-license|''default-license'']
; [!default-license]''default-license''
: License value to be used when rendering content.
  Can be overwritten in a zettel with [[meta key|00001006020000]] ''license''.
  Default: (the empty string).
; [!default-role|''default-role'']
; [!default-role]''default-role''
: Role to be used, if a zettel specifies no ''role'' [[meta key|00001006020000]].
  Default: ""zettel"".
; [!default-syntax|''default-syntax'']
; [!default-syntax]''default-syntax''
: Syntax to be used, if a zettel specifies no ''syntax'' [[meta key|00001006020000]].
  Default: ""zmk"" (""[[Zettelmarkup|00001007000000]]"").
; [!default-title|''default-title'']
; [!default-title]''default-title''
: Title to be used, if a zettel specifies no ''title'' [[meta key|00001006020000]].
  Default: ""Untitled"".

  You can use all [[inline-structured elements|00001007040000]] of Zettelmarkup.
; [!default-visibility|''default-visibility'']
; [!default-visibility]''default-visibility''
: Visibility to be used, if zettel does not specify a value for the [[''visibility''|00001006020000#visibility]] metadata key.
  Default: ""login"".
; [!expert-mode|''expert-mode'']
: If set to a [[boolean true value|00001006030500]], all zettel with [[visibility ""expert""|00001010070200]] will be shown (to the owner, if [[authentication is enabled|00001010040100]]; to all, otherwise).
; [!expert-mode]''expert-mode''
: If set to a boolean true value, all zettel with [[visibility ""expert""|00001010070200]] will be shown (to the owner, if [[authentication is enabled|00001010040100]]; to all, otherwise).
  This affects most computed zettel.
  Default: ""False"".
; [!footer-html|''footer-html'']
; [!footer-html]''footer-html''
: Contains some HTML code that will be included into the footer of each Zettelstore web page.
  It only affects the [[web user interface|00001014000000]].
  Zettel content, delivered via the [[API|00001012000000]] as JSON, etc. is not affected.
  Default: (the empty string).
; [!home-zettel|''home-zettel'']
; [!home-zettel]''home-zettel''
: Specifies the identifier of the zettel, that should be presented for the default view / home view.
  If not given or if the identifier does not identify a zettel, the zettel with the identifier ''00010000000000'' is shown.
; [!marker-external|''marker-external'']
; [!marker-external]''marker-external''
: Some HTML code that is displayed after a [[reference to external material|00001007040310]].
  Default: ""&\#10138;"", to display a ""➚"" sign.
; [!max-transclusions|''max-transclusions'']
; [!max-transclusions]''max-transclusions''
: Maximum number of indirect transclusion.
  This is used to avoid an exploding ""transclusion bomb"", a form of a [[billion laughs attack|https://en.wikipedia.org/wiki/Billion_laughs_attack]].
  Default: ""1024"".
; [!site-name|''site-name'']
; [!site-name]''site-name''
: Name of the Zettelstore instance.
  Will be used when displaying some lists.
  Default: ""Zettelstore"".
; [!yaml-header|''yaml-header'']
: If [[true|00001006030500]], metadata and content will be separated by ''---\\n'' instead of an empty line (''\\n\\n'').
; [!yaml-header]''yaml-header''
: If true, metadata and content will be separated by ''-\--\\n'' instead of an empty line (''\\n\\n'').
  Default: ""False"".

  You will probably use this key, if you are working with another software processing [[Markdown|https://daringfireball.net/projects/markdown/]] that uses a subset of [[YAML|https://yaml.org/]] to specify metadata.
; [!zettel-file-syntax|''zettel-file-syntax'']
; [!zettel-file-syntax]''zettel-file-syntax''
: If you create a new zettel with a syntax different to ""zmk"", Zettelstore will store the zettel as two files:
  one for the metadata (file without a filename extension) and another for the content (file extension based on the syntax value).
  If you want to specify alternative syntax values, for which you want new zettel to be stored in one file (file extension ''.zettel''), you can use this key.
  All values are case-insensitive, duplicate values are removed.

  For example, you could use this key if you're working with Markdown syntax and you want to store metadata and content in one ''.zettel'' file.

  If ''yaml-header'' evaluates to true, a zettel is always stored in one ''.zettel'' file.

id: 00001004051000
title: The ''run'' sub-command
role: manual
tags: #command #configuration #manual #zettelstore
syntax: zmk
modified: 20220214175947
modified: 20211124140711

=== ``zettelstore run``
This starts the web service.

```
zettelstore run [-a PORT] [-c CONFIGFILE] [-d DIR] [-debug] [-p PORT] [-r] [-v]
```

; [!a|''-a PORT'']
; [!a]''-a PORT''
: Specifies the TCP port through which you can reach the [[administrator console|00001004100000]].
  See the explanation of [[''admin-port''|00001004010000#admin-port]] for more details.
; [!c|''-c CONFIGFILE'']
; [!c]''-c CONFIGFILE''
: Specifies ''CONFIGFILE'' as a file, where [[startup configuration data|00001004010000]] is read.
  It is ignored, when the given file is not available, nor readable.

  Default: ''./.zscfg''. (''.\\.zscfg'' on Windows)), where ''.'' denotes the ""current directory"".
; [!d|''-d DIR'']
; [!d]''-d DIR''
: Specifies ''DIR'' as the directory that contains all zettel.

  Default is ''./zettel'' (''.\\zettel'' on Windows), where ''.'' denotes the ""current directory"".
; [!debug|''-debug'']
; [!debug]''-debug''
: Allows better debugging of the internal web server by disabling any timeout values.
  You should specify this only as a developer.
  Especially do not enable it for a production server.

  [[https://blog.cloudflare.com/exposing-go-on-the-internet/#timeouts]] contains a good explanation for the usefulness of sensitive timeout values.
; [!p|''-p PORT'']
; [!p]''-p PORT''
: Specifies the integer value ''PORT'' as the TCP port, where the Zettelstore web server listens for requests.

  Default: 23123.

  Zettelstore listens only on ''127.0.0.1'', e.g. only requests from the current computer will be processed.
  If you want to listen on network card to process requests from other computer, please use [[''listen-addr''|00001004010000#listen-addr]] of the configuration file as described below.
; [!r|''-r'']
; [!r]''-r''
: Puts the Zettelstore in read-only mode.
  No changes are possible via the [[web user interface|00001014000000]] / via the [[API|00001012000000]].

  This allows to publish your content without any risks of unauthorized changes.
; [!v|''-v'']
; [!v]''-v''
: Be more verbose when writing logs.

Command line options take precedence over [[configuration file|00001004010000]] options.

id: 00001004051100
title: The ''run-simple'' sub-command
role: manual
tags: #command #configuration #manual #zettelstore
syntax: zmk
modified: 20220214180253
modified: 20210712234203

=== ``zettelstore run-simple``
This sub-command is implicitly called, when an user starts Zettelstore by double-clicking on its GUI icon.
It is s simplified variant of the [[''run'' sub-command|00001004051000]].

It allows only to specify a zettel directory.
The directory will be created automatically, if it does not exist.
This is a difference to the ''run'' sub-command, where the directory must exists.
In contrast to the ''run'' sub-command, other command line parameter are not allowed.

```
zettelstore run-simple [-d DIR]
```

; [!d|''-d DIR'']
; [!d]''-d DIR''
: Specifies ''DIR'' as the directory that contains all zettel.

  Default is ''./zettel'' (''.\\zettel'' on Windows), where ''.'' denotes the ""current directory"".

id: 00001004051200
title: The ''file'' sub-command
role: manual
tags: #command #configuration #manual #zettelstore
syntax: zmk
modified: 20220209114650
modified: 20210727120507

Reads zettel data from a file (or from standard input / stdin) and renders it to standard output / stdout.
This allows Zettelstore to render files manually.
```
zettelstore file [-t FORMAT] [file-1 [file-2]]
```

; ''-t FORMAT''
: Specifies the output format.
  Supported values are:
  [[''html''|00001012920510]] (default),
  [[''djson''|00001012920503]],
  [[''native''|00001012920513]],
  [[''text''|00001012920519]],
  [[''zjson''|00001012920503]],
  and [[''zmk''|00001012920522]].
; ''file-1''
: Specifies the file name, where at least metadata is read.
  If ''file-2'' is not given, the zettel content is also read from here.
; ''file-2''
: File name where the zettel content is stored.

If neither ''file-1'' nor ''file-2'' are given, metadata and zettel content are read from standard input / stdin.

id: 00001004101000
title: List of supported commands of the administrator console
role: manual
tags: #configuration #manual #zettelstore
syntax: zmk
modified: 20220218133526
modified: 20211210184654

; [!bye|''bye'']
; ''bye''
: Closes the connection to the administrator console.
; [!config|''config SERVICE'']
; ''config SERVICE''
: Displays all valid configuration keys for the given service.

  If a key ends with the hyphen-minus character (""''-''"", U+002D), the key denotes a list value.
  If a key ends with the hyphen-minus character (""''-''"", ''U+002D''), the key denotes a list value.
  Keys of list elements are specified by appending a number greater than zero to the key.
; [!crlf|''crlf'']
; ''crlf''
: Toggles CRLF mode for console output.
  Changes end of line sequences between Windows mode (==\\r\\n==) and non-Windows mode (==\\n==, initial value).
  Often used on Windows telnet clients that otherwise scramble the output of commands.
; [!dump-index|''dump-index'']
; ''dump-index''
: Displays the content of the internal search index.
; [!dump-recover|''dump-recover RECOVER'']
; ''dump-recover RECOVER''
: Displays data about the last given recovered internal activity.

  The value for ''RECOVER'' can be obtained via the command ``stat core``, which lists all overview data about all recoveries.
; [!echo|''echo'']
; ''echo''
: Toggles the echo mode, where each command is printed before execution.
; [!end-profile|''end-profile'']
; ''end-profile''
: Stops profiling the application.
; [!env|''env'']
; ''env''
: Display environment values.
; [!help|''help'']
; ''help''
: Displays a list of all available commands.
; [!get-config|''get-config'']
; ''get-config''
: Displays current configuration data.

  ``get-config`` shows all current configuration data.

  ``get-config SERVICE`` shows only the current configuration data of the given service.

  ``get-config SERVICE KEY`` shows the current configuration data for the given service and key.
; [!header|''header'']
; ''header''
: Toggles the header mode, where each table is show with a header nor not.
; [!log-level|''log-level'']
; [!log-level]''log-level''
: Displays or sets the [[logging level|00001004059700]] for the kernel or a service.

  ``log-level`` shows all known log level.

  ``log-level NAME`` shows log level for the given service or for the kernel.

  ``log-level NAME VALUE`` sets the log level for the given service or for the kernel.
  ''VALUE'' is either the name of the log level or its numerical value.
; [!metrics|''metrics'']
; ''metrics''
: Displays some values that reflect the inner workings of Zettelstore.
  See [[here|https://golang.org/pkg/runtime/metrics/]] for a technical description of these values.
; [!next-config|''next-config'']
; ''next-config''
: Displays next configuration data.
  It will be the current configuration, if the corresponding services is restarted.

  ``next-config`` shows all next configuration data.

  ``next-config SERVICE`` shows only the next configuration data of the given service.

  ``next-config SERVICE KEY`` shows the next configuration data for the given service and key.
; [!profile|''profile [PROFILE] [FILE]'']
; ''profile [PROFILE] [FILE]''
: Starts to profile the software with the profile PROFILE and writes profiling data to file FILE.
  If PROFILE is not given, a value ''CPU'' is assumed, which specifies to profile CPU usage.
  If FILE is not given, a value ''PROFILE.prof'' will be used.

  Other values for ''PROFILE'' are: ''goroutine'', ''heap'', ''allocs'', ''threadcreate'', ''block'', and ''mutex''.
  In the future, more values may be appropriate.
  See the [[Go documentation|https://pkg.go.dev/runtime/pprof#Profile]] for details.

  This feature is dependent on the internal implementation language of Zettelstore, Go.
  It may be removed without any further notice at any time.
  In most cases, it is a tool for software developers to optimize Zettelstore's internal workings.
; [!restart|''restart SERVICE'']
; ''restart SERVICE''
: Restart the given service and all other that depend on this.
; [!services|''services'']
; ''services''
: Displays s list of all available services and their current status.
; [!set-config|''set-config SERVICE KEY VALUE'']
; ''set-config SERVICE KEY VALUE''
: Sets a single configuration value for the next configuration of a given service.
  It will become effective if the service is restarted.

  If the key specifies a list value, all other list values with a number greater than the given key are deleted.
  You can use the special number ""0"" to delete all values.
  E.g. ``set-config box box-uri-0 any_text`` will remove all values of the list __box-uri-__.
; [!shutdown|''shutdown'']
; ''shutdown''
: Terminate the Zettelstore itself (and closes the connection to the administrator console).
; [!start|''start SERVICE'']
: Start the given service and all dependent services.
; [!stat|''stat SERVICE'']
; ''start SERVICE''
: Start the given bservice and all dependent services.
; ''stat SERVICE''
: Display some statistical values for the given service.
; [!stop|''stop SERVICE'']
; ''stop SERVICE''
: Stop the given service and all other that depend on this.

id: 00001006010000
title: Syntax of Metadata
role: manual
tags: #manual #syntax #zettelstore
syntax: zmk
modified: 20220218131923
modified: 20211103164152

The metadata of a zettel is a collection of key-value pairs.
The syntax roughly resembles the internal header of an email ([[RFC5322|https://tools.ietf.org/html/rfc5322]]).

The key is a sequence of alphanumeric characters, a hyphen-minus character (""''-''"", U+002D) is also allowed.
The key is a sequence of alphanumeric characters, a hyphen-minus character (""''-''"") is also allowed.
It begins at the first position of a new line.

A key is separated from its value either by
* a colon character (""'':''""),
* a non-empty sequence of space characters,
* a sequence of space characters, followed by a colon, followed by a sequence of space characters.

id: 00001006020000
title: Supported Metadata Keys
role: manual
tags: #manual #meta #reference #zettel #zettelstore
syntax: zmk
modified: 20220218130146
modified: 20220111103609

Although you are free to define your own metadata, by using any key (according to the [[syntax|00001006010000]]), some keys have a special meaning that is enforced by Zettelstore.
See the [[computed list of supported metadata keys|00000000000090]] for details.

Most keys conform to a [[type|00001006030000]].

; [!all-tags|''all-tags'']
; [!all-tags]''all-tags''
: A property (a computed values that is not stored) that contains both the value of [[''tags''|#tags]] together with all [[tags|00001007040000#tag]] that are specified within the content.
; [!back|''back'']
; [!back]''back''
: Is a property that contains the identifier of all zettel that reference the zettel of this metadata, that are not referenced by this zettel.
  Basically, it is the value of [[''backward''|#bachward]], but without any zettel identifier that is contained in [[''forward''|#forward]].
; [!backward|''backward'']
; [!backward]''backward''
: Is a property that contains the identifier of all zettel that reference the zettel of this metadata.
  References within invertible values are not included here, e.g. [[''precursor''|#precursor]].
; [!box-number|''box-number'']
; [!box-number]''box-number''
: Is a computed value and contains the number of the box where the zettel was found.
  For all but the [[predefined zettel|00001005090000]], this number is equal to the number __X__ specified in startup configuration key [[''box-uri-__X__''|00001004010000#box-uri-x]].
; [!copyright|''copyright'']
; [!copyright]''copyright''
: Defines a copyright string that will be encoded.
  If not given, the value ''default-copyright'' from the  [[configuration zettel|00001004020000#default-copyright]] will be used.
; [!credential|''credential'']
; [!credential]''credential''
: Contains the hashed password, as it was emitted by [[``zettelstore password``|00001004051400]].
  It is internally created by hashing the password, the [[zettel identifier|00001006050000]], and the value of the ''ident'' key.

  It is only used for zettel with a ''role'' value of ""user"".
; [!dead|''dead'']
; [!dead]''dead''
: Property that contains all references that does __not__ identify a zettel.
; [!folge|''folge'']
; [!folge]''folge''
: Is a property that contains identifier of all zettel that reference this zettel through the [[''precursor''|#precursor]] value.
; [!forward|''forward'']
; [!forward]''forward''
: Property that contains all references that identify another zettel within the content of the zettel.
; [!id|''id'']
; [!id]''id''
: Contains the [[zettel identifier|00001006050000]], as given by the Zettelstore.
  It cannot be set manually, because it is a computed value.
; [!lang|''lang'']
; [!lang]''lang''
: Language for the zettel.
  Mostly used for HTML rendering of the zettel.
  If not given, the value ''default-lang'' from the  [[configuration zettel|00001004020000#default-lang]] will be used.
  Use values according to the language definition of [[RFC-5646|https://tools.ietf.org/html/rfc5646]].
; [!license|''license'']
; [!license]''license''
: Defines a license string that will be rendered.
  If not given, the value ''default-license'' from the [[configuration zettel|00001004020000#default-license]] will be used.
; [!modified|''modified'']
; [!modified]''modified''
: Date and time when a zettel was modified through Zettelstore.
  If you edit a zettel with an editor software outside Zettelstore, you should set it manually to an appropriate value.

  This is a computed value.
  There is no need to set it via Zettelstore.
; [!no-index]''no-index''
: If set to a ""true"" value, the zettel will not be indexed and therefore not be found in full-text searches.
; [!precursor|''precursor'']
; [!precursor]''precursor''
: References zettel for which this zettel is a ""Folgezettel"" / follow-up zettel.
  Basically the inverse of key [[''folge''|#folge]].
; [!published|''published'']
; [!published]''published''
: This property contains the timestamp of the mast modification / creation of the zettel.
  If [[''modified''|#modified]] is set, it contains the same value.
  Otherwise, if the zettel identifier contains a valid timestamp, the identifier is used.
  In all other cases, this property is not set.

  It can be used for [[sorting|00001012052000]] zettel based on their publication date.

  It is a computed value.
  There is no need to set it via Zettelstore.
; [!read-only|''read-only'']
; [!read-only]''read-only''
: Marks a zettel as read-only.
  The interpretation of [[supported values|00001006020400]] for this key depends, whether authentication is [[enabled|00001010040100]] or not.
; [!role|''role'']
; [!role]''role''
: Defines the role of the zettel.
  Can be used for selecting zettel.
  See [[supported zettel roles|00001006020100]].
  If not given, the value ''default-role'' from the [[configuration zettel|00001004020000#default-role]] will be used.
; [!syntax|''syntax'']
; [!syntax]''syntax''
: Specifies the syntax that should be used for interpreting the zettel.
  The zettel about [[other markup languages|00001008000000]] defines supported values.
  If not given, the value ''default-syntax'' from the [[configuration zettel|00001004020000#default-syntax]] will be used.
; [!tags|''tags'']
; [!tags]''tags''
: Contains a space separated list of tags to describe the zettel further.
  Each Tag must begin with the number sign character (""''#''"", U+0023).
; [!title|''title'']
  Each Tag must begin with the number sign character (""''#''"", ''U+0023'').
; [!title]''title''
: Specifies the title of the zettel.
  If not given, the value ''default-title'' from the [[configuration zettel|00001004020000#default-title]] will be used.

  You can use all [[inline-structured elements|00001007040000]] of Zettelmarkup.
; [!url|''url'']
; [!url]''url''
: Defines an URL / URI for this zettel that possibly references external material.
  One use case is to specify the document that the current zettel comments on.
  The URL will be rendered special in the [[web user interface|00001014000000]] if you use the default template.
; [!useless-files|''useless-files'']
; [!useless-files]''useless-files''
: Contains the file names that are rejected to serve the content of a zettel.
  Is used for [[directory boxes|00001004011400]] and [[file boxes|00001004011200#file]].
  If a zettel is renamed or deleted, these files will be deleted.
; [!user-id|''user-id'']
; [!user-id]''user-id''
: Provides some unique user identification for an [[user zettel|00001010040200]].
  It is used as a user name for authentication.

  It is only used for zettel with a ''role'' value of ""user"".
; [!user-role|''user-role'']
; [!user-role]''user-role''
: Defines the basic privileges of an authenticated user, e.g. reading / changing zettel.
  Is only valid in a user zettel.

  See [[User roles|00001010070300]] for more details.
; [!visibility|''visibility'']
; [!visibility]''visibility''
: When you work with authentication, you can give every zettel a value to decide, who can see the zettel.
  Its default value can be set with [[''default-visibility''|00001004020000#default-visibility]] of the configuration zettel.

  See [[visibility rules for zettel|00001010070200]] for more details.

id: 00001006020100
title: Supported Zettel Roles
role: manual
tags: #manual #meta #reference #zettel #zettelstore
syntax: zmk
modified: 20220214174553
modified: 20211127174441

The [[''role'' key|00001006020000#role]] defines what kind of zettel you are writing.
You are free to define your own roles.

The role ''zettel'' is predefined as the default role, but you can [[change this|00001004020000#default-role]].

Some roles are defined for technical reasons:

; [!configuration|''configuration'']
; [!configuration]''configuration''
: A zettel that contains some configuration data for the Zettelstore.
  Most prominent is [[00000000000100]], as described in [[00001004020000]].
; [!manual|''manual'']
; [!manual]''manual''
: All zettel that document the inner workings of the Zettelstore software.
  This role is only used in this specific Zettelstore.

If you adhere to the process outlined by Niklas Luhmann, a zettel could have one of the following three roles:

; [!note|''note'']
; [!note]''note''
: A small note, to remember something.
  Notes are not real zettel, they just help to create a real zettel.
  Think of them as Post-it notes.
; [!literature|''literature'']
; [!literature]''literature''
: Contains some remarks about a book, a paper, a web page, etc.
  You should add a citation key for citing it.
; [!zettel|''zettel'']
; [!zettel]''zettel''
: A real zettel that contains your own thoughts.

However, you are free to define additional roles, e.g. ''material'' for literature that is web-based only, ''slide'' for presentation slides, ''paper'' for the text of a scientific paper, ''project'' to define a project, ...

id: 00001006030000
title: Supported Key Types
role: manual
tags: #manual #meta #reference #zettel #zettelstore
syntax: zmk
modified: 20220304114106
modified: 20220110161544

All [[supported metadata keys|00001006020000]] conform to a type.

User-defined metadata keys conform also to a type, based on the suffix of the key.

|=Suffix|Type
| ''-number'' | [[Number|00001006033000]]
| ''-role'' | [[Word|00001006035500]]
| ''-set'' | [[WordSet|00001006036000]]
| ''-title'' | [[Zettelmarkup|00001006036500]]
| ''-url'' | [[URL|00001006035000]]
| ''-zettel''  | [[Identifier|00001006032000]]
| ''-zid''  | [[Identifier|00001006032000]]
| ''-zids''  | [[IdentifierSet|00001006032500]]
| any other suffix | [[EString|00001006031500]]

The name of the metadata key is bound to the key type

Every key type has an associated validation rule to check values of the given type.
There is also a rule how values are matched, e.g. against a search term when selecting some zettel.
And there is a rule how values compare for sorting.

* [[Boolean|00001006030500]]
* [[Credential|00001006031000]]
* [[EString|00001006031500]]
* [[Identifier|00001006032000]]
* [[IdentifierSet|00001006032500]]
* [[Number|00001006033000]]
* [[String|00001006033500]]
* [[TagSet|00001006034000]]
* [[Timestamp|00001006034500]]
* [[URL|00001006035000]]
* [[Word|00001006035500]]
* [[WordSet|00001006036000]]
* [[Zettelmarkup|00001006036500]]

id: 00001006030500
title: Boolean Value
title: Boolean Key Type
role: manual
tags: #manual #reference #zettel #zettelstore
tags: #manual #meta #reference #zettel #zettelstore
syntax: zmk
modified: 20220304114040

On some places, metadata values are interpreted as a truth value.
Values of this type denote a truth value.

=== Allowed values
Every character sequence that begins with a ""0"", ""F"", ""N"", ""f"", or a ""n"" is interpreted as the boolean ""false"" value.
All values are interpreted as the boolean ""true"" value.
Every character sequence that begins with a ""''0''"", ""''F''"", ""''N''"", ""''f''"", or a ""''n''"" is interpreted as the ""false"" boolean value.
All other metadata value is interpreted as the ""true"" boolean value.

=== Match operator
The match operator is the equals operator, i.e.
* ``(true == true) == true``
* ``(false == false) == true``
* ``(true == false) == false``
* ``(false == true) == false``
However, there is no full support for a boolean type.
Such values are interpreted as a [[string value|00001006033500]], e.g. with respect to comparing and sorting.

=== Sorting
The ""false"" value is less than the ""true"" value: ``false < true``

id: 00001006034000
title: TagSet Key Type
role: manual
tags: #manual #meta #reference #zettel #zettelstore
syntax: zmk
modified: 20220218130413
modified: 20220111103723

Values of this type denote a (sorted) set of tags.

A set is different to a list, as no duplicate values are allowed.

=== Allowed values
Every tag must must begin with the number sign character (""''#''"", U+0023), followed by at least one printable character.
Every tag must must begin with the number sign character (""''#''"", ''U+0023''), followed by at least one printable character.
Tags are separated by space characters.

All characters are mapped to their lower case values.

=== Match operator
It depends of the first character of a search string how it is matched against a tag set value:

id: 00001007020000
title: Zettelmarkup: Basic Definitions
role: manual
tags: #manual #zettelmarkup #zettelstore
syntax: zmk
modified: 20220218130713
modified: 20211124175237

Every Zettelmarkup content consists of a sequence of Unicode code-points.
Unicode code-points are called in the following as **character**s.
Every zettelmark content consists of a sequence of Unicode codepoints.
Unicode codepoints are called in the following as **character**s.

Characters are encoded with UTF-8.

; Line
: A __line__ is a sequence of characters, except newline (U+000A) and carriage return (U+000D), followed by a line ending sequence or the end of content.
: A __line__ is a sequence of characters, except newline (''U+000A'') and carraige return (''U+000D''), followed by a line ending sequence or the end of content.
; Line ending
: A __line ending__ is either a newline not followed by a carriage return, a newline followed by a carriage return, or a carriage return.
  Different line can be finalized by different line endings.
; Empty line
: An __empty line__ is an empty sequence of characters, followed by a line ending or the end of content.
; Space character
: The __space character__ is the Unicode code-point U+0020.
: The __space character__ is the Unicode codepoint ''U+0020''.

id: 00001007030100
title: Zettelmarkup: Description Lists
role: manual
tags: #manual #zettelmarkup #zettelstore
syntax: zmk
modified: 20220218131155
modified: 20211124172247

A description list is a sequence of terms to be described together with the descriptions of each term.
Every term can described in multiple ways.

A description term (short: __term__) is specified with one semicolon (""'';''"", U+003B) at the first position, followed by a space character and the described term, specified as a sequence of line elements.
A description term (short: __term__) is specified with one semicolon (""'';''"", ''U+003B'') at the first position, followed by a space character and the described term, specified as a sequence of line elements.
If the following lines should also be part of the term, exactly two spaces must be given at the beginning of each following line.

The description of a term is given with one colon (""'':''"", U+003A) at the first position, followed by a space character and the description itself, specified as a sequence of [[inline elements|00001007040000]].
The description of a term is given with one colon (""'':''"", ''U+003A'') at the first position, followed by a space character and the description itself, specified as a sequence of [[inline elements|00001007040000]].
Similar to terms, following lines can also be part of the actual description, if they begin at each line with exactly two space characters.

In contrast to terms, the actual descriptions are merged into a paragraph.
This is because, an actual description can contain more than one paragraph.
As usual, paragraphs are separated by an empty line.
Every following paragraph of an actual description must be indented by two space characters.

id: 00001007030200
title: Zettelmarkup: Nested Lists
role: manual
tags: #manual #zettelmarkup #zettelstore
syntax: zmk
modified: 20220218133902
modified: 20211124172337

There are thee kinds of lists that can be nested: ordered lists, unordered lists, and quotation lists.

Ordered lists are specified with the number sign (""''#''"", U+0023), unordered lists use the asterisk (""''*''"", U+002A), and quotation lists are specified with the greater-than sing (""''>''"", U+003E).
Ordered lists are specified with the number sign (""''#''"", ''U+0023''), unordered lists use the asterisk (""''*''"", ''U+002A''), and quotation lists are specified with the greater-than sing (""''>''"", ''U+003E'').
Let's call these three characters __list characters__.

Any nested list item is specified by a non-empty sequence of list characters, followed by a space character and a sequence of [[inline elements|00001007040000]].
In case of a quotation list as the last list character, the space character followed by a sequence of inline elements is optional.
The number / count of list characters gives the nesting of the lists.
If the following lines should also be part of the list item, exactly the same number of spaces must be given at the beginning of each of the following lines as it is the lists are nested, plus one additional space character.
In other words: the inline elements must begin at the same column as it was on the previous line.

id: 00001007030300
title: Zettelmarkup: Headings
role: manual
tags: #manual #zettelmarkup #zettelstore
syntax: zmk
modified: 20220218133755
modified: 20211124172401

To specify a (sub-) section of a zettel, you should use the headings syntax: at
the beginning of a new line type at least three equal signs (""''=''"", U+003D), plus at least one
the beginning of a new line type at least three equal signs (""''=''"", ''U+003D''), plus at least one
space and enter the text of the heading as [[inline elements|00001007040000]].

```zmk
=== Level 1 Heading
==== Level 2 Heading
===== Level 3 Heading
====== Level 4 Heading

id: 00001007030400
title: Zettelmarkup: Horizontal Rules / Thematic Break
role: manual
tags: #manual #zettelmarkup #zettelstore
syntax: zmk
modified: 20220218133651
modified: 20211124174251

To signal a thematic break, you can specify a horizontal rule.
This is done by entering at least three hyphen-minus characters (""''-''"", U+002D) at the first position of a line.
To signal a thematic break, you can specify a horizonal rule.
This is done by entering at least three hyphen-minus characters (""''-''"", ''U+002D'') at the first position of a line.
You can add some [[attributes|00001007050000]], although the horizontal rule does not support the default attribute.
Any other character in this line will be ignored

If you do not enter the three hyphen-minus character at the very first position of a line, the are interpreted as [[inline elements|00001007040000]], typically as an ""en-dash" followed by a hyphen-minus.
If you do not enter the three hyphen-minus charachter at the very first position of a line, the are interpreted as [[inline elements|00001007040000]], typically as an ""en-dash" followed by a hyphen-minus.

Example:

```zmk
---
----{.zs-deprecated}
----{color=green}
-----
 --- inline
--- ignored
```
is rendered in HTML as
:::example
---
----{.zs-deprecated}
----{color=green}
-----
 --- inline
--- ignored
:::

id: 00001007030500
title: Zettelmarkup: Verbatim Blocks
role: manual
tags: #manual #zettelmarkup #zettelstore
syntax: zmk
modified: 20220218131500
modified: 20211124170510

Verbatim blocks are used to enter text that should not be interpreted.
They begin with at least three grave accent characters (""''`''"", U+0060) at the first position of a line.
Alternatively, a modifier letter grave accent (""''ˋ''"", U+02CB) is also allowed[^On some devices, such as an iPhone / iPad, a grave accent character is harder to enter and is often confused with a modifier letter grave accent.].
They begin with at least three grave accent characters (""''`''"", ''U+0060'') at the first position of a line.
Alternatively, a modifier letter grave accent (""''ˋ''"", ''U+02CB'') is also allowed[^On some devices, such as an iPhone / iPad, a grave accent character is harder to enter and is often confused with a modifier letter grave accent.].

You can add some [[attributes|00001007050000]] on the beginning line of a verbatim block, following the initiating characters.
The verbatim block supports the default attribute: when given, all spaces in the text are rendered in HTML as open box characters (U+2423).
The verbatim block supports the default attribute: when given, all spaces in the text are rendered in HTML as open box characters (""''␣''"", ''U+2423'').
If you want to give only one attribute and this attribute is the generic attribute, you can omit the most of the attribute syntax and just specify the value.
It will be interpreted as a ([[programming|00001007050200]]) language to support colorizing the text when rendered in HTML.

Any other character in this line will be ignored

Text following the beginning line will not be interpreted, until a line begins with at least the same number of the same characters given at the beginning line.
This allows to enter some grave accent characters in the text that should not be interpreted.

id: 00001007030600
title: Zettelmarkup: Quotation Blocks
role: manual
tags: #manual #zettelmarkup #zettelstore
syntax: zmk
modified: 20220218131806
modified: 20211124174017

A simple way to enter a quotation is to use the [[quotation list|00001007030200]].
A quotation list loosely follows the convention of quoting text within emails.
However, if you want to attribute the quotation to seomeone, a quotation block is more appropriately.

This kind of line-range block begins with at least three less-than characters (""''<''"", U+003C) at the first position of a line.
This kind of line-range block begins with at least three less-than characters (""''<''"", ''U+003C'') at the first position of a line.
You can add some [[attributes|00001007050000]] on the beginning line of a quotation block, following the initiating characters.
The quotation does not support the default attribute, nor the generic attribute.
Attributes are interpreted on HTML rendering.
Any other character in this line will be ignored

Text following the beginning line will be interpreted, until a line begins with at least the same number of the same characters given at the beginning line.
This allows to enter a quotation block within a quotation block.

id: 00001007030700
title: Zettelmarkup: Verse Blocks
role: manual
tags: #manual #zettelmarkup #zettelstore
syntax: zmk
modified: 20220218132432
role: manual

Sometimes, you want to enter text with significant space characters at the beginning of each line and with significant line endings.
Poetry is one typical example.
Of course, you could help yourself with hard space characters and hard line breaks, by entering a backslash character before a space character and at the end of each line.
Using a verse block might be easier.

This kind of line-range block begins with at least three quotation mark characters (""''"''"", U+0022) at the first position of a line.
This kind of line-range block begins with at least three quotation mark characters (""''"''"", ''U+0022'') at the first position of a line.
You can add some [[attributes|00001007050000]] on the beginning line of a verse block, following the initiating characters.
The verse block does not support the default attribute, nor the generic attribute.
Attributes are interpreted on HTML rendering.
Any other character in this line will be ignored.

Text following the beginning line will be interpreted, until a line begins with at least the same number of the same characters given at the beginning line.
This allows to enter a verse block within a verse block.
At the ending line, you can enter some [[inline elements|00001007040000]] after the quotation mark characters.
These will interpreted as some attribution text.

For example:

```zmk
""""
A verse block with
 an
  embedded
   verse block
"""{.zs-deprecated}
"""{style=color:green}
Embedded
  verse
block
""" Embedded Author
"""" Verse Author
```
will be rendered as:
:::example
""""
A verse block with
 an
  embedded
   verse block
"""{.zs-deprecated}
"""{style=color:green}
Embedded
  verse
block
""" Embedded Author
"""" Verse Author
:::

id: 00001007030800
title: Zettelmarkup: Region Blocks
role: manual
tags: #manual #zettelmarkup #zettelstore
syntax: zmk
modified: 20220218131131
modified: 20211124173940

Region blocks does not directly have a visual representation.
They just group a range of lines.
You can use region blocks to enter [[attributes|00001007050000]] that apply only to this range of lines.
One example is to enter a multi-line warning that should be visible.

This kind of line-range block begins with at least three colon characters (""'':''"", U+003A) at the first position of a line[^Since a [[description text|00001007030100]] only use exactly one colon character at the first position of a line, there is no possible ambiguity between these elements.].
This kind of line-range block begins with at least three colon characters (""'':''"", ''U+003A'') at the first position of a line[^Since a [[description text|00001007030100]] only use exactly one colon character at the first position of a line, there is no possible ambiguity between these elements.].
You can add some [[attributes|00001007050000]] on the beginning line of a region block, following the initiating characters.
The region block does not support the default attribute, but it supports the generic attribute.
Some generic attributes, like ``=note``, ``=warning`` will be rendered special.
Attributes are interpreted on HTML rendering.
Any other character in this line will be ignored.

Text following the beginning line will be interpreted, until a line begins with at least the same number of the same characters given at the beginning line.

id: 00001007030900
title: Zettelmarkup: Comment Blocks
role: manual
tags: #manual #zettelmarkup #zettelstore
syntax: zmk
modified: 20220218130330
role: manual

Comment blocks are quite similar to [[verbatim blocks|00001007030500]]: both are used to enter text that should not be interpreted.
While the text entered inside a verbatim block will be processed somehow, text inside a comment block will be ignored[^Well, not completely ignored: text is read, but it will typically not rendered visible.].
Comment blocks are typically used to give some internal comments, e.g. the license of a text or some internal remarks.

Comment blocks begin with at least three percent sign characters (""''%''"", U+0025) at the first position of a line.
Comment blocks begin with at least three percent sign characters (""''%''"", ''U+0025'') at the first position of a line.
You can add some [[attributes|00001007050000]] on the beginning line of a comment block, following the initiating characters.
The comment block supports the default attribute: when given, the text will be rendered, e.g. as an HTML comment.
When rendered to JSON, the comment block will not be ignored but it will output some JSON text.
Same for other renderers.

Any other character in this line will be ignored

id: 00001007031000
title: Zettelmarkup: Tables
role: manual
tags: #manual #zettelmarkup #zettelstore
syntax: zmk
modified: 20220218131107
modified: 20211124174218

Tables are used to show some data in a two-dimenensional fashion.
In zettelmarkup, table are not specified explicitly, but by entering __table rows__.
Therefore, a table can be seen as a sequence of table rows.
A table row is nothing as a sequence of __table cells__.
The length of a table is the number of table rows, the width of a table is the maximum length of its rows.

The first cell of a row must begin with the vertical bar character (""''|''"", U+007C) at the first position of a line.
The first cell of a row must begin with the vertical bar character (""''|''"", ''U+007C'') at the first position of a line.
The other cells of a row begin with the same vertical bar character at later positions in that line.
A cell is delimited by the vertical bar character of the next cell or by the end of the current line.
A vertical bar character as the last character of a line will not result in a table cell.
It will be ignored.
Inside a cell, you can specify any [[inline elements|00001007040000]].

For example:
```zmk
| a1 | a2 | a3|
| b1 | b2 | b3
| c1 | c2
```
will be rendered in HTML as:
:::example
| a1 | a2 | a3|
| b1 | b2 | b3
| c1 | c2
:::

=== Header row
If any cell in the first row of a table contains an equal sing character (""''=''"", U+003D) as the very first character, then this first row will be interpreted as a __table header__ row.
If any cell in the first row of a table contains an equal sing character (""''=''"", ''U+003D'') as the very first character, then this first row will be interpreted as a __table header__ row.

For example:
```zmk
| a1 | a2 |= a3|
| b1 | b2 | b3
| c1 | c2
```
will be rendered in HTML as:
:::example
| a1 | a2 |= a3|
| b1 | b2 | b3
| c1 | c2
:::

=== Column alignment
Inside a header row, you can specify the alignment of each header cell by a given character as the last character of a cell.
The alignment of a header cell determines the alignment of every cell in the same column.
The following characters specify the alignment:

* the colon character (""'':''"", U+003A) forces a centered alignment,
* the less-than sign character (""''<''"", U+0060) specifies an alignment to the left,
* the greater-than sign character (""''>''"", U+0062) will produce right aligned cells.
* the colon character (""'':''"", ''U+003A'') forces a centered aligment,
* the less-than sign character (""''<''"", ''U+0060'') specifies an alignment to the left,
* the greater-than sign character (""''>''"", ''U+0062'') will produce right aligned cells.

If no alignment character is given, a default alignment is used.

For example:
```zmk
|=Left<|Right>|Center:|Default
|123456|123456|123456|123456|

|=Left<|Right>|Center:|Default
|>R|:C|<L
|123456|123456|123456|123456|
|123|123|123|123
:::

=== Rows to be ignored
A line that begins with the sequence ''|%'' (vertical bar character (""''|''"", U+007C), followed by a percent sign character (“%”, U+0025)) will be ignored.
A line that begins with the sequence ''|%'' (vertical bar character (""''|''"", ''U+007C''), followed by a percent sign character (“%”, U+0025)) will be ignored.
For example, this allows to specify a horizontal rule that is not rendered.
Such tables are emitted by some commands of the [[administrator console|00001004100000]].
For example, the command ``get-config box`` will emit:
```
|=Key        | Value  | Description
|%-----------+--------+---------------------------
| defdirtype | notify | Default directory box type

id: 00001007031100
title: Zettelmarkup: Transclusion
role: manual
tags: #manual #zettelmarkup #zettelstore
syntax: zmk
modified: 20220218133058
modified: 20220201133837

A transclusion allows to include the content of another zettel into the current zettel just by referencing the other zettel.

The transclusion specification begins with three consecutive left curly bracket characters (""''{''"", U+007B) at the first position of a line and ends with three consecutive right curly bracket characters (""''}''"", U+007D).
The transclusion specification begins with three consecutive left curly bracket characters (""''{''"", ''U+007B'') at the first position of a line and ends with three consecutive right curly bracket characters (""''}''"", ''U+007D'').
The curly brackets delimit the [[zettel identifier|00001006050000]] to be included.

First, the referenced zettel is read.
If it contains some transclusions itself, these will be expanded, recursively.
When a recursion is detected, expansion does not take place.
Instead an error message replaces the transclude specification.

id: 00001007031200
title: Zettelmarkup: Inline-Zettel Block
role: manual
tags: #manual #zettelmarkup #zettelstore
syntax: zmk
modified: 20220218172121
modified: 20220201151458

An inline-zettel block allows to specify some content with another syntax without creating a new zettel.
This is useful, for example, if you want to specify a [[simple drawing|00001008050000]] within your zettel and you are sure that you do not need the drawing in another context.
Another example is to embed some [[Markdown|00001008010500]] content, because you are too lazy to translate Markdown into Zettelmarkup.[^However, translating into Zettelmarkup is quite easy with the [[zmk encoder|00001012920522]].]
A last example is to specify HTML code to use it for some kind of web frontend framework.

As all other [[line-range blocks|00001007030000#line-range-blocks]], an inline-zettel block begins with at least three identical characters, starting at the first position of a line.
For inline-zettel blocks, the at-sign character (""''@''"", U+0040) is used.
For inline-zettel blocks, the at-sign character (""''@''"", ''U+0040'') is used.

You can add some [[attributes|00001007050000]] on the beginning line of a verbatim block, following the initiating characters.
The inline-zettel block uses the attribute key ""syntax"" to specify the [[syntax|00001008000000]] of the inline-zettel.
Alternatively, you can use the generic attribute to specify the syntax value.
If no value is provided, ""draw"" is assumed.

Any other character in this first line will be ignored.

@@@
:::

Using HTML:
```zmk
@@@html
<h1>H1 Heading</h1>
Alea iacta est
@@@
```
will a section heading of level 1, which is not allowed within Zettelmarkup:
:::example
@@@html
<h1>H1 Heading</h1>
Alea iacta est
@@@
:::
:::note
Please note: some HTML code will not be fully rendered because of possible security implications.
This include HTML lines that contain a ''<script>'' tag or an ''<iframe>'' tag.
:::
Of course, you do not need to switch the syntax and you are allowed to nest inline-zettel blocks:

id: 00001007040000
title: Zettelmarkup: Inline-Structured Elements
role: manual
tags: #manual #zettelmarkup #zettelstore
syntax: zmk
modified: 20220218131736
modified: 20220201150815

Most characters you type is concerned with inline-structured elements.
The content of a zettel contains is many cases just ordinary text, lightly formatted.
Inline-structured elements allow to format your text and add some helpful links or images.
Sometimes, you want to enter characters that have no representation on your keyboard.

; Text formatting

  This kind of reference may be a link, or an images that is display inline when the zettel is rendered.
  Footnotes sometimes factor out some useful text that hinders the flow of reading text.
  Internal marks allow to reference something within a zettel.
  An important aspect of all knowledge work is to reference others work, e.g. with citation keys.
  All these elements can be subsumed under [[reference-like text|00001007040300]].

=== Other inline elements
==== Comment
A comment begins with two consecutive percent sign characters (""''%''"", U+0025).
==== Comments
A comment begins with two consecutive percent sign characters (""''%''"", ''U+0025'').
It ends at the end of the line where it begins.

==== Backslash
The backslash character (""''\\''"", U+005C) gives the next character another meaning.
* If a space character follows, it is converted in a non-breaking space (U+00A0).
The backslash character (""''\\''"", ''U+005C'') gives the next character another meaning.
* If a space character follows, it is converted in a non-breaking space (''U+00A0'').
* If a line ending follows the backslash character, the line break is converted from a __soft break__ into a __hard break__.
* Every other character is taken as itself, but without the interpretation of a Zettelmarkup element.
  For example, if you want to enter a ""'']''"" into a [[footnote text|00001007040330]], you should escape it with a backslash.

==== Tag
Any text that begins with a number sign character (""''#''"", U+0023), followed by a non-empty sequence of Unicode letters, Unicode digits, the hyphen-minus character (""''-''"", U+002D), or the low line character (""''_''"", U+005F) is interpreted as an __inline tag__.
Any text that begins with a number sign character (""''#''"", ''U+0023''), followed by a non-empty sequence of Unicode letters, Unicode digits, the hyphen-minus character (""''-''"", ''U+002D''), or the low line character (""''_''"", ''U+005F'') is interpreted as an __inline tag__.
They are be considered equivalent to tags in metadata.

==== Entities & more
Sometimes it is not easy to enter special characters.
If you know the Unicode code point of that character, or its name according to the [[HTML standard|https://html.spec.whatwg.org/multipage/named-characters.html]], you can enter it by number or by name.

Regardless which method you use, an entity always begins with an ampersand character (""''&''"", U+0026) and ends with a semicolon character (""'';''"", U+003B).
Regardless which method you use, an entity always begins with an ampersand character (""''&''"", ''U+0026'') and ends with a semicolon character (""'';''"", ''U+003B'').
If you know the HTML name of the character you want to enter, put it between these two character.
Example: ``&`` is rendered as ::&::{=example}.

If you want to enter its numeric code point, a number sign character must follow the ampersand character, followed by digits to base 10.
Example: ``&`` is rendered in HTML as ::&::{=example}.

You also can enter its numeric code point as a hex number, if you put the letter ""x"" after the numeric sign character.
Example: ``&`` is rendered in HTML as ::&::{=example}.

Since some Unicode character are used quite often, a special notation is introduced for them:

* Two consecutive hyphen-minus characters result in an __en-dash__ character.
  It is typically used in numeric ranges.
  ``pages 4--7`` will be rendered in HTML as: ::pages 4--7::{=example}.
  Alternative specifications are: ``–``, ``&x8211``, and ``&#x2013``.
* Three consecutive full stop characters (""''.''"", U+002E) after a space result in an horizontal ellipsis character.
* Three consecutive full stop characters (""''.''"", ''U+002E'') after a space result in an horizontal ellipsis character.
  ``to be continued ... later`` will be rendered in HTML as: ::to be continued, ... later::{=example}.
  Alternative specifications are: ``…``, ``&x8230``, and ``&#x2026``.

id: 00001007040100
title: Zettelmarkup: Text Formatting
role: manual
tags: #manual #zettelmarkup #zettelstore
syntax: zmk
modified: 20220218131003
modified: 20211113193440

Text formatting is the way to make your text visually different.
Every text formatting element begins with two same characters.
It ends when these two same characters occur the second time.
It is possible that some [[attributes|00001007050000]] follow immediately, without any separating character.

Text formatting can be nested, up to a reasonable limit.

The following characters begin a text formatting:

* The low line character (""''_''"", U+005F) emphasizes its text.
* The low line character (""''_''"", ''U+005F'') emphasizes its text.
** Example: ``abc __def__ ghi`` is rendered in HTML as: ::abc __def__ ghi::{=example}.
* The asterisk character (""''*''"", U+002A) strongly emphasized its enclosed text.
* The asterisk character (""''*''"", ''U+002A'') strongly emphasized its enclosed text.
** Example: ``abc **def** ghi`` is rendered in HTML as: ::abc **def** ghi::{=example}.
* The greater-than sign character (""''>''"", U+003E) marks text as inserted.
* The greater-than sign character (""''>''"", ''U+003E'') marks text as inserted.
** Example: ``abc >>def>> ghi`` is rendered in HTML as: ::abc >>def>> ghi::{=example}.
* Similar, the tilde character (""''~''"", U+007E) marks deleted text.
* Similar, the tilde character (""''~''"", ''U+007E'') marks deleted text.
** Example: ``abc ~~def~~ ghi`` is rendered in HTML as: ::abc ~~def~~ ghi::{=example}.
* The apostrophe character (""''\'''"", ''U+0027'') renders text in mono-space / fixed font width.
** Example: ``abc ''def'' ghi`` is rendered in HTML as: ::abc ''def'' ghi::{=example}.
* The circumflex accent character (""''^''"", U+005E) allows to enter superscripted text.
* The circumflex accent character (""''^''"", ''U+005E'') allows to enter superscripted text.
** Example: ``e=mc^^2^^`` is rendered in HTML as: ::e=mc^^2^^::{=example}.
* The comma character (""'',''"", U+002C) produces subscripted text.
* The comma character (""'',''"", ''U+002C'') produces subscripted text.
** Example: ``H,,2,,O`` is rendered in HTML as: ::H,,2,,O::{=example}.
* The less-than sign character (""''<''"", ''U+003C'') marks an inline quotation.
** Example: ``<<To be or not<<`` is rendered in HTML as: ::<<To be or not<<::{=example}.
* The quotation mark character (""''"''"", U+0022) marks an inline quotation, according to the [[specified language|00001007050100]].
* The quotation mark character (""''"''"", ''U+0022'') produces the right typographic quotation marks according to the [[specified language|00001007050100]].
** Example: ``""To be or not""`` is rendered in HTML as: ::""To be or not""::{=example}.
** Example: ``""Sein oder nicht""{lang=de}`` is rendered in HTML as: ::""Sein oder nicht""{lang=de}::{=example}.
* The colon character (""'':''"", U+003A) mark some text that should belong together. It fills a similar role as [[region blocks|00001007030800]], but just for inline elements.
* The colon character (""'':''"", ''U+003A'') mark some text that should belong together. It fills a similar role as [[region blocks|00001007030800]], but just for inline elements.
** Example: ``abc ::def::{=example} ghi`` is rendered in HTML as: abc ::def::{=example} ghi.

id: 00001007040200
title: Zettelmarkup: Literal-like formatting
role: manual
tags: #manual #zettelmarkup #zettelstore
syntax: zmk
modified: 20220218131420
modified: 20220201152059

There are some reasons to mark text that should be rendered as uninterpreted:
* Mark text as literal, sometimes as part of a program.
* Mark text as input you give into a computer via a keyboard.
* Mark text as output from some computer, e.g. shown at the command line.

=== Literal text
Literal text somehow relates to [[verbatim blocks|00001007030500]]: their content should not be interpreted further, but may be rendered special.
It is specified by two grave accent characters (""''`''"", U+0060), followed by the text, followed by again two grave accent characters, optionally followed by an [[attribute|00001007050000]] specification.
Similar to the verbatim block, the literal element allows also a modifier letter grave accent (""''ˋ''"", U+02CB) as an alternative to the grave accent character[^On some devices, such as an iPhone / iPad, a grave accent character is harder to enter and is often confused with a modifier letter grave accent.].
It is specified by two grave accent characters (""''`''"", ''U+0060''), followed by the text, followed by again two grave accent characters, optionally followed by an [[attribute|00001007050000]] specification.
Similar to the verbatim block, the literal element allows also a modifier letter grave accent (""''ˋ''"", ''U+02CB'') as an alternative to the grave accent character[^On some devices, such as an iPhone / iPad, a grave accent character is harder to enter and is often confused with a modifier letter grave accent.].
However, all four characters must be the same.

The literal element supports the default attribute: when given, all spaces in the text are rendered in HTML as open box characters (U+2423).
The literal element supports the default attribute: when given, all spaces in the text are rendered in HTML as open box characters (""''␣''"", ''U+2423'').
The use of a generic attribute allows to specify a ([[programming|00001007050200]]) language that controls syntax coloring when rendered in HTML.

If you want to specify a grave accent character in the text, either use modifier grave accent characters as delimiters for the element, or put a backslash character before the grave accent character you want to use inside the element.
If you want to enter a backslash character, you need to enter two of these.

Examples:
* ``\`\`abc def\`\``` is rendered in HTML as ::``abc def``::{=example}.
* ``\`\`abc def\`\`{-}`` is rendered in HTML as ::``abc def``{-}::{=example}.
* ``\`\`abc\\\`def\`\``` is rendered in HTML as ::``abc\`def``::{=example}.
* ``\`\`abc\\\\def\`\``` is rendered in HTML as ::``abc\\def``::{=example}.

=== Computer input
To mark text as input into a computer program, delimit your text with two apostrophe characters (""''\'''"", U+0027) on each side.
=== Keyboard input
To mark text as input into a computer program, delimit your text with two plus sign characters (""''+''"", ''U+002B'') on each side.

Example:
* ``''STRG-C''`` renders in HTML as ::''STRG-C''::{=example}.
* ``''STRG C''{-}`` renders in HTML as ::''STRG C''{-}::{=example}.
* ``++STRG-C++`` renders in HTML as ::++STRG-C++::{=example}.
* ``++STRG C++{-}`` renders in HTML as ::++STRG C++{-}::{=example}.

Attributes can be specified, the default attribute has the same semantic as for literal text.

=== Computer output
To mark text as output from a computer program, delimit your text with two equal sign characters (""''=''"", U+003D) on each side.
To mark text as output from a computer program, delimit your text with two equal sign characters (""''=''"", ''U+003D'') on each side.

Examples:
* ``==The result is: 42==`` renders in HTML as ::==The result is: 42==::{=example}.
* ``==The result is: 42=={-}`` renders in HTML as ::==The result is: 42=={-}::{=example}.

Attributes can be specified, the default attribute has the same semantic as for literal text.

=== Inline-zettel snippet
To specify an inline snippet in a different [[syntax|00001008000000]], delimit your text with two at-sign characters (""''@''"", U+0040) on each side.
To specify an inline snippet in a different [[syntax|00001008000000]], delimit your text with two at-sign characters (""''@''"", ''U+0040'') on each side.

You can add some [[attributes|00001007050000]] immediate after the two closing at-sign characters to specify the syntax to use.
Either use the attribute key ""syntax"" or use the generic attribute to specify the syntax value.
If no value is provided, ""draw"" is assumed.

Examples:
* ``A @@-->@@ B`` renders in HTML as ::A @@-->@@ B::{=example}.
* ``@@<small>@@{=html}Small@@</small>@@{=html}`` renders in HTML as ::@@<small>@@{=html}Small@@</small>@@{=html}::{=example}.

To some degree, an inline-zettel snippet is the @@<small>@@{=html}smaller@@</small>@@{=html} sibling of the [[inline-zettel block|00001007031200]].
For HTML syntax, the same rules apply.

id: 00001007040310
title: Zettelmarkup: Links
role: manual
tags: #manual #zettelmarkup #zettelstore
syntax: zmk
modified: 20220218131639
modified: 20211124172143

There are two kinds of links, regardless of links to (internal) other zettel or to (external) material.
Both kinds begin with two consecutive left square bracket characters (""''[''"", U+005B) and ends with two consecutive right square bracket characters (""'']''"", U+005D).
Both kinds begin with two consecutive left square bracket characters (""''[''"", ''U+005B'') and ends with two consecutive right square bracket characters (""'']''"", ''U+005D'').

The first form provides some text plus the link specification, delimited by a vertical bar character (""''|''"", U+007C): ``[[text|linkspecification]]``.
The first form provides some text plus the link specification, delimited by a vertical bar character (""''|''"", ''U+007C''): ``[[text|linkspecification]]``.

The second form just provides a link specification between the square brackets.
Its text is derived from the link specification, e.g. by interpreting the link specification as text: ``[[linkspecification]]``.

The link specification for another zettel within the same Zettelstore is just the [[zettel identifier|00001006050000]].
To reference some content within a zettel, you can append a number sign character (""''#''"", U+0023) and the name of the mark to the zettel identifier.
To reference some content within a zettel, you can append a number sign character (""''#''"", ''U+0023'') and the name of the mark to the zettel identifier.
The resulting reference is called ""zettel reference"".

To specify some material outside the Zettelstore, just use an normal Uniform Resource Identifier (URI) as defined by [[RFC\ 3986|https://tools.ietf.org/html/rfc3986]].
If the URL begins with the slash character (""/"", U+002F), or if it begins with ""./"" or with ""../"", i.e. without scheme, user info, and host name, the reference will be treated as a ""local reference"", otherwise as an ""external reference"".
If the URL begins with the slash character (""/"", ''U+002F''), or if it begins with ""./"" or with ""../"", i.e. without scheme, user info, and host name, the reference will be treated as a ""local reference"", otherwise as an ""external reference"".
If the URL begins with two slash characters, it will be interpreted relative to the value of [[''url-prefix''|00001004010000#url-prefix]].

The text in the second form is just a sequence of [[inline elements|00001007040000]].

id: 00001007040320
title: Zettelmarkup: Inline Embedding / Transclusion
role: manual
tags: #manual #zettelmarkup #zettelstore
syntax: zmk
modified: 20220218133039
modified: 20220131153953

To some degree, an specification for embedded material is conceptually not too far away from a specification for [[linked material|00001007040310]].
Both contain a reference specification and optionally some text.
In contrast to a link, the specification of embedded material must currently resolve to some kind of real content.
This content replaces the embed specification.

An embed specification begins with two consecutive left curly bracket characters (""''{''"", U+007B) and ends with two consecutive right curly bracket characters (""''}''"", U+007D).
An embed specification begins with two consecutive left curly bracket characters (""''{''"", ''U+007B'') and ends with two consecutive right curly bracket characters (""''}''"", ''U+007D'').
The curly brackets delimits either a reference specification or some text, a vertical bar character and the link specification, similar to a link.

One difference to a link: if the text was not given, an empty string is assumed.

The reference must point to some content, either zettel content or URL-referenced content.
If the referenced zettel does not exist, or is not readable, a [[spinning emoji|00000000040001]] is presented as a visual hint:
 
Example: ``{{00000000000000}}`` will be rendered as ::{{00000000000000}}::{=example}.

There are two kind of content:
# [[image content|00001007040322]],
# [[textual content|00001007040324]].

id: 00001007040322
title: Zettelmarkup: Image Embedding
role: manual
tags: #manual #zettelmarkup #zettelstore
syntax: zmk
modified: 20220214180955
modified: 20211103163657

Image content is assumed, if an URL is used or if the referenced zettel contains an image.

Supported formats are:

* Portable Network Graphics (""PNG""), as defined by [[RFC\ 2083|https://tools.ietf.org/html/rfc2083]].
* Graphics Interchange Format (""GIF"), as defined by [[https://www.w3.org/Graphics/GIF/spec-gif89a.txt]].
* JPEG / JPG, defined by the __Joint Photographic Experts Group__.
* Scalable Vector Graphics (SVG), defined by [[https://www.w3.org/Graphics/SVG/]]

If the text is given, it will be interpreted as an alternative textual representation, to help persons with some visual disabilities.

[[Attributes|00001007050000]] are supported.
They must follow the last right curly bracket character immediately.
One prominent example is to specify an explicit title attribute that is shown on certain web browsers when the zettel is rendered in HTML:

Examples:
* [!spin|``{{Spinning Emoji|00000000040001}}{title=Emoji width=30}``] is rendered as ::{{Spinning Emoji|00000000040001}}{title=Emoji width=30}::{=example}.
* [!spin] ``{{Spinning Emoji|00000000040001}}{title=Emoji width=30}`` is rendered as ::{{Spinning Emoji|00000000040001}}{title=Emoji width=30}::{=example}.
* The above image is also the placeholder for a non-existent zettel:
** ``{{00000000009999}}`` will be rendered as ::{{00000000009999}}::{=example}.

id: 00001007040330
title: Zettelmarkup: Footnotes
role: manual
tags: #manual #zettelmarkup #zettelstore
syntax: zmk
modified: 20220218130100

A footnote begins with a left square bracket, followed by a circumflex accent (""''^''"", U+005E), followed by some text, and ends with a right square bracket.
A footnote begins with a left square bracket, followed by a circumflex accent (""''^''"", ''U+005E''), followed by some text, and ends with a right square bracket.

Example:

``Main text[^Footnote text.].`` is rendered in HTML as: ::Main text[^Footnote text.].::{=example}.

id: 00001007040340
title: Zettelmarkup: Citation Key
role: manual
tags: #manual #zettelmarkup #zettelstore
syntax: zmk
modified: 20220218133447
modified: 20211124172111

A citation key references some external material that is part of a bibliografical collection.

Currently, Zettelstore implements this only partially, it is ""work in progress"".

However, the syntax is: beginning with a left square bracket and followed by an at sign character (""''@''"", U+0040), a the citation key is given.
However, the syntax is: beginning with a left square bracket and followed by an at sign character (""''@''"", ''U+0040''), a the citation key is given.
The key is typically a sequence of letters and digits.
If a comma character (""'',''"", U+002C) or a vertical bar character is given, the following is interpreted as [[inline elements|00001007040000]].
If a comma character (""'',''"", ''U+002C'') or a vertical bar character is given, the following is interpreted as [[inline elements|00001007040000]].
A right square bracket ends the text and the citation key element.

id: 00001007040350
title: Zettelmarkup: Mark
role: manual
tags: #manual #zettelmarkup #zettelstore
syntax: zmk
modified: 20220218133206
modified: 20211103163338

A mark allows to name a point within a zettel.
This is useful if you want to reference some content in a zettel, either with a [[link|00001007040310]] or with an [[inline-mode transclusion|00001007040324]].
This is useful if you want to reference some content in a bigger-sized zettel, currently with a [[link|00001007040310]] only[^Other uses of marks will be given, if Zettelmarkup is extended by a concept called __transclusion__.].

A mark begins with a left square bracket, followed by an exclamation mark character (""''!''"", U+0021).
A mark begins with a left square bracket, followed by an exclamation mark character (""''!''"", ''U+0021'').
Now the optional mark name follows.
It is a (possibly empty) sequence of Unicode letters, Unicode digits, the hyphen-minus character (""''-''"", U+002D), or the low-line character (""''_''"", U+005F).
It is a (possibly empty) sequence of Unicode letters, Unicode digits, the hyphen-minus character (""''-''"", ''U+002D''), or the low-line character (""''_''"", ''U+005F'').
An optional text to be explicitly marked is introduced with a vertical bar character (""''|''"", U+007C), followed by some [[inline-structured elements|00001007040000]].
The mark element ends with a right square bracket.

Examples:
* ``[!]`` is a mark without a name, the empty mark.
* ``[!mark]`` is a mark with the name ""mark"".
* ``[!|some text]``is the empty mark with ""some text"".
* ``[!mark|some text]``is a mark with the name ""mark"" and with ""some text"" that is marked.

id: 00001007050000
title: Zettelmarkup: Attributes
role: manual
tags: #manual #zettelmarkup #zettelstore
syntax: zmk
modified: 20220218132935
modified: 20211124174947

Attributes allows to modify the way how material is presented.
Alternatively, they provide additional information to markup elements.
To some degree, attributes are similar to [[HTML attributes|https://html.spec.whatwg.org/multipage/dom.html#global-attributes]].

Typical use cases for attributes are to specify the (natural) [[language|00001007050100]] for a text region, to specify the [[programming language|00001007050200]] for highlighting program code, or to make white space visible in plain text.

Attributes are specified within curly brackets ``{...}``.
Of course, more than one attribute can be specified.
Attributes are separated by a sequence of space characters or by a comma character.

An attribute normally consists of an optional key and an optional value.
The key is a sequence of letters, digits, a hyphen-minus (""''-''"", U+002D, and a low line / underscore (""''_''"", U+005D).
The key is a sequence of letters, digits, a hyphen-minus (""''-''"", ''U+002D'', and a low line / underscore (""''_''"", ''U+005D'').
It can be empty.
The value is a sequence of any character, except space and the right curly bracket (""''}''"", U+007D).
If the value must contain a space or the right curly bracket, the value can be specified within two quotation marks (""''"''"", U+0022).
The value is a sequence of any character, except space and the right curly bracket (""''}''"", ''U+007D'').
If the value must contain a space or the right curly bracket, the value can be specified within two quotation marks (""''"''"", ''U+0022'').
Within the quotation marks, the backslash character functions as an escape character to specify the quotation mark (and the backslash character too).

Some examples:

* ``{key=value}`` sets the attribute __key__ to value __value__.
* ``{key="value with space"}`` sets the attribute to the given value.
* ``{key="value with quote \\" (and backslash \\\\)"}``
* ``{name}`` sets the attribute __name__.
  It has no corresponding value.
  It is equivalent to ``{name=}``.
* ``{=key}`` sets the __generic attribute__ to the given value.
  It is mostly used for modifying behavior according to a programming language.
  It is mostly used for modifying behaviour according to a programming language.
* ``{.key}`` sets the __class attribute__ to the given value.
  It is equivalent to ``{class=key}``. 

In these examples, ``key`` must conform the the syntax of attribute keys, even if it is used as a value.

If a key is given more than once in an attribute, the values are concatenated (and separated by a space).

* ``{key=value1 key=value2}`` is the same as ``{key"value1 value2"}``.
* ``{key key}`` is the same as ``{key}``.
* ``{.class1 .class2}`` is equivalent to ``{class="class1 class2"}``.

This is not true for the generic attribute.
In ``{=key1 =key2}``, the first key is ignored.
Therefore it is equivalent to ``{=key2}``.

The key ""''-''"" (just hyphen-minus) is special.
It is called __default attribute__ and has a markup specific meaning.
For example, when used for plain text, it replaces the non-visible space with a visible representation:

* ''``Hello, world``{-}'' produces ==Hello, world=={-}.
* ''``Hello, world``'' produces ==Hello, world==.
* ++``Hello, world``{-}++ produces ==Hello, world=={-}.
* ++``Hello, world``++ produces ==Hello, world==.

For some [[block-structured elements|00001007030000]], there is a syntax variant if you only want to specify a generic attribute.
For all line-range blocks you can specify the generic attributes directly in the first line, after the three (or more) block characters.

```
:::attr
...
:::
```
is equivalent to
```
:::{=attr}
...
:::
```.

For other blocks, the closing curly bracket must be on the same line where the block element begins.
However, spaces are allowed between the blocks characters and the attributes.
```
=== Heading {example}
=== Heading {style=color:green}
```
is allowed and equivalent to
```
=== Heading{example}
=== Heading{style=color:green}
```.
But
```
=== Heading {class=example
=== Heading {style=color:green
background=grey}
```
is not allowed. Same for
```
=== Heading {background=color:"
=== Heading {style=color:"
green"}
```.

For [[inline-structued elements|00001007040000]], the attributes must immediately follow the inline markup.
However, the attributes may be continued on the next line when a space or line ending character is possible.

``::GREEN::{example}`` is allowed, but not ``::GREEN:: {example}``.
``::GREEN::{style=color:green}`` is allowed, but not ``::GREEN:: {style=color:green}``.

```
::GREEN::{class=example
::GREEN::{style=color:green
background=grey}
```
is allowed, but not
```
::GREEN::{background=color:
::GREEN::{style=color:
green}
```.

However,
```
::GREEN::{background=color:"
::GREEN::{style=color:"
green"}
```
is allowed, because line endings are allowed within quotes.

=== Reference material
* [[Supported attribute values for natural languages|00001007050100]]
* [[Supported attribute values for programming languages|00001007050200]]

id: 00001007060000
title: Zettelmarkup: Summary of Formatting Characters
role: manual
tags: #manual #reference #zettelmarkup #zettelstore
syntax: zmk
modified: 20220218124943
modified: 20220201151829

The following table gives an overview about the use of all characters that begin a markup element.

|= Character :|= [[Blocks|00001007030000]] <|= [[Inlines|00001007040000]] <
| ''!''  | (free) | (free)
| ''"''  | [[Verse block|00001007030700]] | [[Short inline quote|00001007040100]]
| ''"''  | [[Verse block|00001007030700]] | [[Typographic quotation mark|00001007040100]]
| ''#''  | [[Ordered list|00001007030200]] | [[Tag|00001007040000]]
| ''$''  | (reserved) | (reserved)
| ''%''  | [[Comment block|00001007030900]] | [[Comment|00001007040000]]
| ''&''  | (free) | [[Entity|00001007040000]]
| ''\'''  | (free)  | [[Computer input|00001007040200]]
| ''\'''  | (free)  | [[Monospace text|00001007040100]]
| ''(''  | (free) | (free)
| '')''  | (free) | (free)
| ''*''  | [[Unordered list|00001007030200]] | [[strongly emphasized text|00001007040100]]
| ''+''  | (free) | (free)
| ''+''  | (free) | [[Keyboard input|00001007040200]]
| '',''  | (free) | [[Subscripted text|00001007040100]]
| ''-''  | [[Horizonal rule|00001007030400]] | ""[[en-dash|00001007040000]]""
| ''.''  | (free) | [[Horizontal ellipsis|00001007040000]]
| ''/''  | (free) | (free)
| '':''  | [[Region block|00001007030800]] / [[description text|00001007030100]] | [[Inline region|00001007040100]]
| '';''  | [[Description term|00001007030100]] | [[Small text|00001007040100]]
| ''<''  | [[Quotation block|00001007030600]] | (free)
| ''<''  | [[Quotation block|00001007030600]] | [[Short inline quote|00001007040100]]
| ''=''  | [[Headings|00001007030300]] | [[Computer output|00001007040200]]
| ''>''  | [[Quotation lists|00001007030200]] | [[Inserted text|00001007040100]]
| ''?''  | (free) | (free)
| ''@''  | [[Inline-Zettel blocks|00001007031200]] | [[Inline-zettel snippets|00001007040200#inline-zettel-snippet]]
| ''[''  | (reserved)  | [[Linked material|00001007040300]], [[citation key|00001007040300]], [[footnote|00001007040300]], [[mark|00001007040300]]
| ''\\'' | (blocked by inline meaning) | [[Escape character|00001007040000]]
| '']''  | (reserved) | End of [[link|00001007040300]], [[citation key|00001007040300]], [[footnote|00001007040300]], [[mark|00001007040300]]

id: 00001008000000
title: Other Markup Languages
role: manual
tags: #manual #zettelstore
syntax: zmk
modified: 20220214180202
modified: 20220131141205

[[Zettelmarkup|00001007000000]] is not the only markup language you can use to define your content.
Zettelstore is quite agnostic with respect to markup languages.
Of course, Zettelmarkup plays an important role.
However, with the exception of zettel titles, you can use any (markup) language that is supported:

* CSS
* HTML template data
* Image formats: GIF, PNG, JPEG, SVG
* Markdown
* Plain text, not further interpreted

The [[metadata key|00001006020000#syntax]] ""''syntax''"" specifies which language should be used.
If it is not given, the key ""''default-syntax''"" will be used (specified in the [[configuration zettel|00001004020000#default-syntax]]).
The following syntax values are supported:

; [!css|''css'']
; [!css]''css''
: A [[Cascading Style Sheet|https://www.w3.org/Style/CSS/]], to be used when rendering a zettel as HTML.
; [!draw|''draw'']
; [!draw]''draw''
: A simple [[language|00001008050000]] to ""draw"" a graphic by using some simple Unicode characters.
; [!gif|''gif'']; [!jpeg|''jpeg'']; [!jpg|''jpg'']; [!png|''png'']
; [!gif]''gif''; [!jpeg]''jpeg''; [!jpg]''jpg''; [!png]''png''
: The formats for pixel graphics.
  Typically the data is stored in a separate file and the syntax is given in the metafile, which has the same name as the zettel identifier and has no file extension.[^Before version 0.2.0, the metafile had the file extension ''.meta'']
; [!html|''html'']
; [!html]''html''
: Hypertext Markup Language, will not be parsed further.
  Instead, it is treated as [[text|#text]], but will be encoded differently for [[HTML format|00001012920510]] (same for the [[web user interface|00001014000000]]).

  For security reasons, equivocal elements will not be encoded in the HTML format / web user interface, e.g. the ``<script ...`` tag.
  See [[security aspects of Markdown|00001008010000#security-aspects]] for some details.
; [!markdown|''markdown''], [!md|''md'']
; [!markdown]''markdown'', [!md]''md''
: For those who desperately need [[Markdown|https://daringfireball.net/projects/markdown/]].
  Since the world of Markdown is so diverse, a [[CommonMark|00001008010500]] parser is used.
  See [[Use Markdown within Zettelstore|00001008010000]].
; [!mustache|''mustache'']
; [!mustache]''mustache''
: A [[Mustache template|https://mustache.github.io/]], used when rendering a zettel as HTML for the [[web user interface|00001014000000]].
; [!none|''none'']
; [!none]''none''
: Only the metadata of a zettel is ""parsed"".
  Useful for displaying the full metadata.
  The [[runtime configuration zettel|00000000000100]] uses this syntax.
  The zettel content is ignored.
; [!svg|''svg'']
; [!svg]''svg''
: A [[Scalable Vector Graphics|https://www.w3.org/TR/SVG2/]].
; [!text|''text''], [!plain|''plain''], [!txt|''txt'']
; [!text]''text'', [!plain]''plain'', [!txt]''txt''
: Just plain text that must not be interpreted further.
; [!zmk|''zmk'']
; [!zmk]''zmk''
: [[Zettelmarkup|00001007000000]].

The actual values are also listed in a zettel named [[Zettelstore Supported Parser|00000000000092]].

If you specify something else, your content will be interpreted as plain text.

id: 00001008050000
title: The ""draw"" language
role: manual
tags: #graphic #manual #zettelstore
syntax: zmk
modified: 20220217180713
modified: 20220201133222

Sometimes, ""a picture is worth a thousand words"".
Sometimes, <<a picture is worth a thousand words<<.
To create some graphical representations, Zettelstore provides a simple mechanism.
Characters like ""''|''"" or ""''-''"" already provide some visual feedback.
For example, to create a picture containing two boxes that are connected via an arrow, the following representation is possible:
```
+-------+       +-------+
| Box 1 | ----> | Box 2 |
+-------+       +-------+

id: 00001010070200
title: Visibility rules for zettel
role: manual
tags: #authorization #configuration #manual #security #zettelstore
syntax: zmk
modified: 20220304114501
modified: 20211126185655

For every zettel you can specify under which condition the zettel is visible to others.
This is controlled with the metadata key [[''visibility''|00001006020000#visibility]].
The following values are supported:

; [!public|""public""]
; [!public]""public""
: The zettel is visible to everybody, even if the user is not authenticated.
; [!login|""login""]
; [!login]""login""
: Only an authenticated user can access the zettel.

  This is the default value for [[''default-visibility''|00001004020000#default-visibility]].
; [!creator|""creator""]
; [!creator]""creator""
: Only an authenticated user that is allowed to create new zettel can access the zettel.
; [!owner|""owner""]
; [!owner]""owner""
: Only the owner of the Zettelstore can access the zettel.

  This is for zettel with sensitive content, e.g. the [[configuration zettel|00001004020000]] or the various zettel that contains the templates for rendering zettel in HTML.
; [!expert|""expert""]
: Only the owner of the Zettelstore can access the zettel, if runtime configuration [[''expert-mode''|00001004020000#expert-mode]] is set to a [[boolean true value|00001006030500]].
; [!expert]""expert""
: Only the owner of the Zettelstore can access the zettel, if runtime configuration [[''expert-mode''|00001004020000#expert-mode]] is set to a boolean true value.

  This is for zettel with sensitive content that might irritate the owner.
  Computed zettel with internal runtime information are examples for such a zettel.

When you install a Zettelstore, only [[some zettel|//h?visibility=public]] have visibility ""public"".
One is the zettel that contains [[CSS|00000000020001]] for displaying the [[web user interface|00001014000000]].
This is to ensure that the web interface looks nice even for not authenticated users.

id: 00001010070300
title: User roles
role: manual
tags: #authorization #configuration #manual #security #zettelstore
syntax: zmk
modified: 20220214175212
modified: 20211124141938

Every user is associated with some basic privileges.
These are specified in the [[user zettel|00001010040200]] with the key ''user-role''.
The following values are supported:

; [!reader|""reader""]
; [!reader]""reader""
: The user is allowed to read zettel.
  This is the default value for any user except the owner of the Zettelstore.
; [!writer|""writer""]
; [!writer]""writer""
: The user is allowed to create new zettel and to change existing zettel.
; [!creator|""creator""]
; [!creator]""creator""
: The user is only allowed to create new zettel.
  It is also allowed to change its own user zettel.

There are two other user roles, implicitly defined:

; The anonymous user
: This role is assigned to any user that is not authenticated.
  Can only read zettel with visibility [[public|00001010070200]], but cannot change them.
; The owner
: The user that is configured to be the owner of the Zettelstore.
  Does not need to specify a user role in its user zettel.
  Is not restricted in the use of Zettelstore, except when a zettel is marked as [[read-only|00001006020400]].

id: 00001010090100
title: External server to encrypt message transport
role: manual
tags: #configuration #encryption #manual #security #zettelstore
syntax: zmk
modified: 20220217180826
modified: 20211027125733

Since Zettelstore does not encrypt the messages it exchanges with its clients, you may need some additional software to enable encryption.

=== Public-key encryption
To enable encryption, you probably use some kind of encryption keys.
In most cases, you need to deploy a ""public-key encryption"" process, where your side publish a public encryption key that only works with a corresponding private decryption key.
Technically, this is not trivial.
Any client who wants to communicate with your Zettelstore must trust the public encryption key.
Otherwise the client cannot be sure that it is communication with your Zettelstore.
This problem is solved in part with [[Let's Encrypt|https://letsencrypt.org/]],
""a free, automated, and open certificate authority (CA), run for the public’s benefit.
It is a service provided by the [[Internet Security Research Group|https://www.abetterinternet.org/]]"".
<<a free, automated, and open certificate authority (CA), run for the public’s benefit.
It is a service provided by the [[Internet Security Research Group|https://www.abetterinternet.org/]]<<.

Alternatively, you can buy these keys for public-key encryption at ""certificate authorities"" or its dealers.

=== Server software for encryption
The solution of placing a server for encryption in front of an encryption-unaware server is a relatively old one.
There are many different alternatives to choose.

First, there are web servers.
Business-grade web servers must enable encryption.
Most of them allow to forward a request unencrypted to another web server.
Some examples:

* [[Apache Web Server|https://httpd.apache.org/]]: enable [[mod_proxy|http://httpd.apache.org/docs/current/mod/mod_proxy.html]] and configure a reverse proxy.
* [[nginx|https://nginx.org/]]: set-up a reverse proxy with the [[''proxy_pass''|https://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_pass]] directive.
* [[Caddy|https://caddyserver.com/]]: see below for details.

Other software is also possible.
There exists software dedicated for this task of handling the encryption part.
Some examples:

* [[stunnel|https://www.stunnel.org/]] (""a proxy designed to add TLS encryption functionality to existing clients and servers without any changes in the programs' code."")
* [[stunnel|https://www.stunnel.org/]] (<<a proxy designed to add TLS encryption functionality to existing clients and servers without any changes in the programs' code.<<)
* [[Traefik|https://traefik.io/]]: set-up a [[router|https://docs.traefik.io/routing/routers/]].

=== Example configuration for Caddy
For the inexperienced owner of a Zettelstore, [[Caddy|https://caddyserver.com/]] is a good option[^In fact, the [[server-based installation procedure|00001003000000]] of Zettelstore was inspired by Caddy.].
Caddy has the capability to automatically fetch appropriately encryption key from Let's Encrypt, without any further configuration.
The only requirement of doing this is that the server must be publicly accessible.

id: 00001012000000
title: API
role: manual
tags: #api #manual #zettelstore
syntax: zmk
modified: 20220304173249
modified: 20220201165200

The API (short for ""**A**pplication **P**rogramming **I**nterface"") is the primary way to communicate with a running Zettelstore.
Most integration with other systems and services is done through the API.
The [[web user interface|00001014000000]] is just an alternative, secondary way of interacting with a Zettelstore.

=== Background
The API is HTTP-based and uses plain text and JSON as its main encoding format for exchanging messages between a Zettelstore and its client software.

=== Working with zettel
* [[Create a new zettel|00001012053200]]
* [[Retrieve metadata and content of an existing zettel|00001012053300]]
* [[Retrieve metadata of an existing zettel|00001012053400]]
* [[Retrieve evaluated metadata and content of an existing zettel in various encodings|00001012053500]]
* [[Retrieve parsed metadata and content of an existing zettel in various encodings|00001012053600]]
* [[Retrieve references of an existing zettel|00001012053700]]
* [[Retrieve context of an existing zettel|00001012053800]]
* [[Retrieve unlinked references to an existing zettel|00001012053900]]
* [[Retrieve zettel order within an existing zettel|00001012054000]]
* [[Update metadata and content of a zettel|00001012054200]]
* [[Rename a zettel|00001012054400]]
* [[Delete a zettel|00001012054600]]

=== Various helper methods
* [[Retrieve administrative data|00001012070500]]
* [[Encode Zettelmarkup inline material as HTML/Text|00001012070500]]
* [[Execute some commands|00001012080100]]
** [[Check for authentication|00001012080200]]
** [[Refresh internal data|00001012080500]]

id: 00001012050600
title: API: Provide an access token
role: manual
tags: #api #manual #zettelstore
syntax: zmk
modified: 20220218130020
modified: 20210830161320

The [[authentication process|00001012050200]] provides you with an [[access token|00001012921000]].
Most API calls need such an access token, so that they know the identity of the caller.

You send the access token in the ""Authorization"" request header field, as described in [[RFC 6750, section 2.1|https://tools.ietf.org/html/rfc6750#section-2.1]].
You need to use the ""Bearer"" authentication scheme to transmit the access token.

For example (in plain text HTTP):
```
GET /z HTTP/1.0
Authorization: Bearer eyJhbGciOiJIUzUxMiJ9.eyJfdGsiOjEsImV4cCI6MTYwMTczMTI3NSwiaWF0IjoxNjAxNzMwNjc1LCJzdWIiOiJhYmMiLCJ6aWQiOiIyMDIwMTAwMzE1MDEwMCJ9.ekhXkvn146P2bMKFQcU-bNlvgbeO6sS39hs6U5EKfjIqnSInkuHYjYAIfUqf_clYRfr6YBlX5izii8XfxV8jhg
```
Note, that there is exactly one space character (""'' ''{-}"", U+0020) between the string ""Bearer"" and the access token: ``Authorization: Bearer eyJhbGciOiJIUzUxMiJ9.ey...``{-}.
Note, that there is exactly one space character (''U+0020'') between the string ""Bearer"" and the access token: ``Authorization: Bearer eyJhbGciOiJIUzUxMiJ9.ey...``{-}.

If you use the [[curl|https://curl.haxx.se/]] tool, you can use the ''-H'' command line parameter to set this header field.
If you use the [[curl|https://curl.haxx.se/]] tool, you can use the ++-H++ command line parameter to set this header field.

id: 00001012051810
title: API: Select zettel based on their metadata
role: manual
tags: #api #manual #zettelstore
syntax: zmk
modified: 20220218133305
modified: 20211121170308

Every query parameter that does __not__ begin with the low line character (""_"", U+005F) is treated as the name of a [[metadata|00001006010000]] key.
Every query parameter that does __not__ begin with the low line character (""_"", ''U+005F'') is treated as the name of a [[metadata|00001006010000]] key.
According to the [[type|00001006030000]] of a metadata key, zettel are possibly selected.
All [[supported|00001006020000]] metadata keys have a well-defined type.
User-defined keys have the type ''e'' (string, possibly empty).

For example, if you want to retrieve all zettel that contain the string ""API"" in its title, your request will be:
```sh
# curl 'http://127.0.0.1:23123/j?title=API'
{"query":"title MATCH API","list":[{"id":"00001012921000","meta":{"title":"API: JSON structure of an access token","tags":"#api #manual #reference #zettelstore","syntax":"zmk","role":"manual"}},{"id":"00001012920500","meta":{"title":"Formats available by the API","tags":"#api #manual #reference #zettelstore","syntax":"zmk","role":"manual"}},{"id":"00001012920000","meta":{"title":"Endpoints used by the API","tags":"#api #manual #reference #zettelstore","syntax":"zmk","role":"manual"}}, ...
```

However, if you want all zettel that does not match a given value, you must prefix the value with the exclamation mark character (""!"", U+0021).
However, if you want all zettel that does not match a given value, you must prefix the value with the exclamation mark character (""!"", ''U+0021'').
For example, if you want to retrieve all zettel that do not contain the string ""API"" in their title, your request will be:
```sh
# curl 'http://127.0.0.1:23123/j?title=!API'
{"query":"title NOT MATCH API","list":[{"id":"00010000000000","meta":{"back":"00001003000000 00001005090000","backward":"00001003000000 00001005090000","copyright":"(c) 2020-2021 by Detlef Stern <ds@zettelstore.de>","forward":"00000000000001 00000000000003 00000000000096 00000000000100","lang":"en","license":"EUPL-1.2-or-later","role":"zettel","syntax":"zmk","title":"Home"}},{"id":"00001014000000","meta":{"back":"00001000000000 00001004020000 00001012920510","backward":"00001000000000 00001004020000 00001012000000 00001012920510","copyright":"(c) 2020-2021 by Detlef Stern <ds@zettelstore.de>","forward":"00001012000000","lang":"en","license":"EUPL-1.2-or-later","published":"00001014000000","role":"manual","syntax":"zmk","tags":"#manual #webui #zettelstore","title":"Web user interface"}},
...
```

id: 00001012051890
title: API: Search syntax (simple)
role: manual
tags: #api #manual #zettelstore
syntax: zmk
modified: 20220218130900
modified: 20211124135846

If the search string starts with the exclamation mark character (""!"", U+0021), it will be removed and the query matches all values that **do not match** the search string.
If the search string starts with the exclamation mark character (""!"", ''U+0021''), it will be removed and the query matches all values that **do not match** the search string.

In the next step, the first character of the search string will be inspected.
If it contains one of the characters ""'':''"", ""''=''"", ""''>''"", ""''<''"", or ""''~''"", this will modify how the search will be performed.
The character will be removed from the start of the search string.

For example, assume the search string is ""def"":

; The colon character (""'':''"", U+003A) (or none of these characters)
; The colon character (""'':''"", ''U+003A'') (or none of these characters)
: This is the __default__ comparison.
  The comparison depends on the type of the underlying values.
  For a content search, it is equal to the tilde character ""''~''"", which returns true if a word within the content just contains the search string.
  For metadata, it depends on the key [[type|00001006030000]].

  It you omit the the comparison character, the default comparison is also used.
; The tilde character (""''~''"", U+007E)
; The tilde character (""''~''"", ''U+007E'')
: The inspected text[^Either all words of the zettel content and/or some metadata values] contains the search string.
  ""def"", ""defghi"", and ""abcdefghi"" are matching the search string.
; The equal sign character (""''=''"", U+003D)
; The equal sign character (""''=''"", ''U+003D'')
: The inspected text must contain a word that is equal to the search string.
  Only the word ""def"" matches the search string.
; The greater-than sign character (""''>''"", U+003E)
; The greater-than sign character (""''>''"", ''U+003E'')
: The inspected text must contain a word with the search string as a prefix.
  A word like ""def"" or ""defghi"" matches the search string.
; The less-than sign character (""''<''"", U+003C)
; The less-than sign character (""''<''"", ''U+003C'')
: The inspected text must contain a word with the search string as a suffix.
  A word like ""def"" or ""abcdef"" matches the search string.

If you want to include an initial ""''!''"" into the search string, you must prefix that with the escape character ""''\\''"".
For example ""\\!abc"" will search for the string ""!abc"".
A similar rule applies to the characters that specify the way how the search will be done.
For example, ""!\\=abc"" will search for content that does not contains the string ""=abc"".

id: 00001012052000
title: API: Sort the list of zettel metadata
role: manual
tags: #api #manual #zettelstore
syntax: zmk
modified: 20220218131937
modified: 20211124175920

If not specified, the list of zettel is sorted descending by the value of the [[zettel identifier|00001006050000]].
The highest zettel identifier, which is a number, comes first.
You change that with the ""''_sort''"" query parameter.
Alternatively, you can also use the ""''_order''"" query parameter.
It is an alias.

Its value is the name of a metadata key, optionally prefixed with a hyphen-minus character (""''-''"", U+002D).
Its value is the name of a metadata key, optionally prefixed with a hyphen-minus character (""-"", ''U+002D'').
According to the [[type|00001006030000]] of a metadata key, the list of zettel is sorted.
If hyphen-minus is given, the order is descending, else ascending.

If you want a random list of zettel, specify the value ""_random"" in place of the metadata key.
""''_sort=_random''"" (or ""''_order=_random''"") is the query parameter in this case.
If can be combined with ""[[''_limit=1''|00001012051830]]"" to obtain just one random zettel.

Currently, only the first occurrence of ''_sort'' is recognized.
In the future it will be possible to specify a combined sort key.

id: 00001012053500
title: API: Retrieve evaluated metadata and content of an existing zettel in various encodings
role: manual
tags: #api #manual #zettelstore
syntax: zmk
modified: 20220301174012
modified: 20211124180519

The [[endpoint|00001012920000]] to work with evaluated metadata and content of a specific zettel is ''/v/{ID}'', where ''{ID}'' is a placeholder for the [[zettel identifier|00001006050000]].

For example, to retrieve some evaluated data about this zettel you are currently viewing, just send a HTTP GET request to the endpoint ''/v/00001012053500''[^If [[authentication is enabled|00001010040100]], you must include the a valid [[access token|00001012050200]] in the ''Authorization'' header].
If successful, the output is a JSON object:
```sh
# curl http://127.0.0.1:23123/v/00001012053500
{"meta":{"title":[{"t":"Text","s":"API:"},{"t":"Space"},{"t":"Text","s":"Retrieve"},{"t":"Space"},{"t":"Text","s":"evaluated"},{"t":"Space"},{"t":"Text","s":"metadata"},{"t":"Space"},{"t":"Text","s":"and"},{"t":"Space"},{"t":"Text","s":"content"},{"t":"Space"},{"t":"Text","s":"of"},{"t":"Space"},{"t":"Text","s":"an"},{"t":"Space"},{"t":"Text","s":"existing"},{"t":"Space"},{"t":"Text","s":"zettel"},{"t":"Space"},{"t":"Text","s":"in"},{"t":"Space"}, ...
```

To select another encoding, you can provide a query parameter ''_enc=[[ENCODING|00001012920500]]''.
The default encoding is ""[[zjson|00001012920503]]"".
The default encoding is ""[[djson|00001012920503]]"".
Others are ""[[html|00001012920510]]"", ""[[text|00001012920519]]"", and some more.
```sh
# curl 'http://127.0.0.1:23123/v/00001012053500?_enc=html'
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>API: Retrieve evaluated metadata and content of an existing zettel in various encodings</title>
<meta name="zs-role" content="manual">
<meta name="keywords" content="api, manual, zettelstore">
<meta name="zs-syntax" content="zmk">
<meta name="zs-back" content="00001012000000">
<meta name="zs-backward" content="00001012000000">
<meta name="zs-box-number" content="1">
<meta name="copyright" content="(c) 2020-2021 by Detlef Stern <ds@zettelstore.de>">
<meta name="zs-forward" content="00001010040100 00001012050200 00001012920000 00001012920800">
<meta name="zs-published" content="00001012053500">
</head>
<body>
<p>The <a href="00001012920000">endpoint</a> to work with evaluated metadata and content of a specific zettel is <kbd>/v/{ID}</kbd>, where <kbd>{ID}</kbd> is a placeholder for the <a href="00001006050000">zettel identifier</a>.</p>
<p>The <a href="00001012920000">endpoint</a> to work with evaluated metadata and content of a specific zettel is <span class="zs-monospace">/v/{ID}</span>, where <span class="zs-monospace">{ID}</span> is a placeholder for the <a href="00001006050000">zettel identifier</a>.</p>
...
```

You also can use the query parameter ''_part=[[PART|00001012920800]]'' to specify which parts of a zettel must be encoded.
In this case, its default value is ''content''.
```sh
# curl 'http://127.0.0.1:23123/v/00001012053500?_enc=html&_part=meta'
<meta name="zs-title" content="API: Retrieve evaluated metadata and content of an existing zettel in various encodings">
<meta name="zs-role" content="manual">
<meta name="keywords" content="api, manual, zettelstore">
<meta name="zs-syntax" content="zmk">
<meta name="zs-back" content="00001012000000">
<meta name="zs-backward" content="00001012000000">
<meta name="zs-box-number" content="1">
<meta name="copyright" content="(c) 2020-2021 by Detlef Stern <ds@zettelstore.de>">
<meta name="zs-forward" content="00001010040100 00001012050200 00001012920000 00001012920800">
<meta name="zs-lang" content="en">
<meta name="zs-published" content="00001012053500">
```

The optional query parameter ''_embed'' will embed all images into the returned encoding.

=== HTTP Status codes
; ''200''
: Retrieval was successful, the body contains an appropriate JSON object.
; ''400''
: Request was not valid. 
  There are several reasons for this.
  Maybe the zettel identifier did not consist of exactly 14 digits or ''_enc'' / ''_part'' contained illegal values.
; ''403''
: You are not allowed to retrieve data of the given zettel.
; ''404''
: Zettel not found.
  You probably used a zettel identifier that is not used in the Zettelstore.

id: 00001012053700
title: API: Retrieve references of an existing zettel
role: manual
tags: #api #manual #zettelstore
syntax: zmk
modified: 20211124180813

The web of zettel is one important value of a Zettelstore.
Many zettel references other zettel, embedded material, external/local material or, via citations, external literature.
By using the [[endpoint|00001012920000]] ''/l/{ID}'' you are able to retrieve these references.

````
# curl http://127.0.0.1:23123/l/00001012053700
{"id":"00001012053700","linked":{"outgoing":["00001012920000","00001007040300#links","00001007040300#embedded-material","00001007040300#citation-key"]},"embedded":{}}
````
Formatted, this translates into:
````json
{
  "id": "00001012053700",
  "linked": {
    "outgoing": [
      "00001012920000",
      "00001007040300#links",
      "00001007040300#embedded-material",
      "00001007040300#citation-key"
    ]
  },
  "embedded": {}
}
````
=== Kind
The following top-level JSON keys are returned:
; ''id''
: The [[zettel identifier|00001006050000]] for which the references were requested.
; ''linked''
: A JSON object that contains information about incoming and outgoing [[links|00001007040300#links]].
; ''embedded''
: A JSON object that contains information about referenced [[embedded material|00001007040300#embedded-material]].
; ''cite''
: A JSON list of [[citation keys|00001007040300#citation-key]] (as JSON strings).

Incoming and outgoing references are basically zettel.
Therefore the list elements are JSON objects with key ''id'', optionally with an appended fragment.
Local and external references are strings.

=== HTTP Status codes
; ''200''
: Retrieval was successful, the body contains an appropriate JSON object.
; ''400''
: Request was not valid. 
  There are several reasons for this.
  Maybe the zettel identifier did not consist of exactly 14 digits.
; ''403''
: You are not allowed to retrieve data of the given zettel.
; ''404''
: Zettel not found.
  You probably used a zettel identifier that is not used in the Zettelstore.

id: 00001012070500
title: Retrieve administrative data
title: API: Encode Zettelmarkup inline material as HTML/Text
role: zettel
tags: #api #manual #zettelstore
syntax: zmk
modified: 20220304174027
modified: 20211230231944

The [[endpoint|00001012920000]] ''/x'' allows you to retrieve some (administrative) data.
To encode [[Zettelmarkup inline material|00001007040000]] send a HTTP POST request to the [[endpoint|00001012920000]] ''/v''.
The POST body must contain a JSON encoded list of Zettelmarkup inline material to be encoded:

; ''first-zmk''
: Contains the first [[Zettelmarkup encoded|00001007000000]] inline-structured elements.
  This will be encoded as [[HTML|00001012920510]] and [[Text|00001012920519]].
; ''other-zmk''
: Contain more material.
  The list can be empty.
  These will be encoded in HTML only.
; ''lang''
: Specifies the language for HTML encoding.
Currently, you can only request Zettelstore version data.
  If empty, the default language of the Zettelstore instance will be used.
; ''no-links''
: A boolean value, which specifies whether links should be encoded (``"no-links":false``) or should be not encoded (``"no-links":true``).
  Default: ''false''.

Typically, this call will be used to encode the [[title|00001006020000#title]] of a zettel.
````

# curl 'http://127.0.0.1:23123/x'
{"major":0,"minor":4,"patch":0,"info":"dev","hash":"cb121cc980-dirty"}
````
If successful, the call will return the following JSON document:

Zettelstore conforms somehow to the Standard [[Semantic Versioning|https://semver.org/]].
; ''first-html''
: HTML encoding of ''first-zmk''
; ''first-text''
: Text encoding of ''first-zmk''
; ''other_html''
: HTML encoding of the corresponding value in ''other-zmk''.

The names ""major"", ""minor"", and ""patch"" are described in this standard.
Encoding takes place in the context of all other zettel in the Zettelstore.
For example, [[links|00001007040310]] and images are evaluated according to this context.

The name ""info"" contains sometimes some additional information, e.g. ""dev"" for a development version, or ""preview"" for a preview version.
A simple example:
```sh
# curl -X POST --data '{"first-zmk":"hallo [[00000000000001]]"}' http://127.0.0.1:23123/v
{"first-html":"hallo <a href=\"00000000000001\">00000000000001</a>","first-text":"hallo ","other-html":null}

The name ""hash"" contains some data to identify the version from a developers perspective.
# curl -X POST --data '{"first-zmk":"hallo [[00000000000001]]","no-links":true}' http://127.0.0.1:23123/v
{"first-html":"hallo <span>00000000000001</span>","first-text":"hallo ","other-html":null}
```

=== HTTP Status codes
; ''200''
: Retrieval was successful, the body contains an appropriate JSON object.
: Operation was successful, the body contains a JSON object as described above.
; ''400''
: Request was not valid. 
  There are several reasons for this.
  Most likely, the JSON was not formed according to above rules.
; ''403''
: You are not allowed to perform this operation.

id: 00001012920000
title: Endpoints used by the API
role: manual
tags: #api #manual #reference #zettelstore
syntax: zmk
modified: 20220304173423
modified: 20211230234616

All API endpoints conform to the pattern ''[PREFIX]LETTER[/ZETTEL-ID]'', where:
; ''PREFIX''
: is the URL prefix (default: ""/""), configured via the ''url-prefix'' [[startup configuration|00001004010000]],
: is the URL prefix (default: ''/''), configured via the ''url-prefix'' [[startup configuration|00001004010000]],
; ''LETTER''
: is a single letter that specifies the resource type,
: is a single letter that specifies the ressource type,
; ''ZETTEL-ID''
: is an optional 14 digits string that uniquely [[identify a zettel|00001006050000]].

The following letters are currently in use:

|= Letter:| Without zettel identifier | With [[zettel identifier|00001006050000]] | Mnemonic
| ''a'' | POST: [[client authentication|00001012050200]] | | **A**uthenticate
|       | PUT: [[renew access token|00001012050400]] |
| ''j'' | GET: [[list zettel AS JSON|00001012051200]] | GET: [[retrieve zettel AS JSON|00001012053300]] | **J**SON
|       | POST: [[create new zettel|00001012053200]] | PUT: [[update a zettel|00001012054200]]
|       |  | DELETE: [[delete the zettel|00001012054600]]
|       |  | MOVE: [[rename the zettel|00001012054400]]
| ''l'' |  | GET: [[list references|00001012053700]] | **L**inks
| ''m'' |  | GET: [[retrieve metadata|00001012053400]] | **M**etadata
| ''o'' |  | GET: [[list zettel order|00001012054000]] | **O**rder
| ''p'' |  | GET: [[retrieve parsed zettel|00001012053600]]| **P**arsed
| ''r'' | GET: [[list roles|00001012052600]] | | **R**oles
| ''t'' | GET: [[list tags|00001012052400]] || **T**ags
| ''u'' |  | GET [[unlinked references|00001012053900]] | **U**nlinked
| ''v'' |  | GET: [[retrieve evaluated zettel|00001012053500]] | E**v**aluated
| ''x'' | GET: [[retrieve administrative data|00001012070500]] | GET: [[list zettel context|00001012053800]] | Conte**x**t
| ''v'' | POST: [[encode inlines|00001012070500]] | GET: [[retrieve evaluated zettel|00001012053500]] | E**v**aluated
| ''x'' | POST: [[execute command|00001012080100]] | GET: [[list zettel context|00001012053800]] | Conte**x**t
|       | POST: [[execute command|00001012080100]]
| ''z'' | GET: [[list zettel|00001012051200#plain]] | GET: [[retrieve zettel|00001012053300#plain]] | **Z**ettel
|       | POST: [[create new zettel|00001012053200#plain]] | PUT: [[update a zettel|00001012054200#plain]]
|       |  | DELETE: [[delete zettel|00001012054600#plain]]
|       |  | MOVE: [[rename zettel|00001012054400#plain]]

The full URL will contain either the ""http"" oder ""https"" scheme, a host name, and an optional port number.
The full URL will contain either the ''http'' oder ''https'' scheme, a host name, and an optional port number.

The API examples will assume the ""http"" schema, the local host ""127.0.0.1"", the default port ""23123"", and the default empty ''PREFIX'' ""/"".
Therefore, all URLs in the API documentation will begin with ""http://127.0.0.1:23123/"".
The API examples will assume the ''http'' schema, the local host ''127.0.0.1'', the default port ''23123'', and the default empty ''PREFIX''.
Therefore, all URLs in the API documentation will begin with ''http://127.0.0.1:23123''.

id: 00001012920500
title: Encodings available via the [[API|00001012000000]]
role: manual
tags: #api #manual #reference #zettelstore
syntax: zmk
modified: 20220209114459
modified: 20211124140517

A zettel representation can be encoded in various formats for further processing.

* [[zjson|00001012920503]] (default)
* [[djson|00001012920503]] (default)
* [[html|00001012920510]]
* [[native|00001012920513]]
* [[text|00001012920519]]
* [[zmk|00001012920522]]

id: 00001012920503
title: ZJSON Encoding
title: DJSON Encoding
role: manual
tags: #api #manual #reference #zettelstore
syntax: zmk
modified: 20220223185826
modified: 20211124134305

A zettel representation that allows to process the syntactic structure of a zettel.
It is a JSON-based encoding format, but different to the structures returned by [[endpoint|00001012920000]] ''/j/{ID}''.

For an example, take a look at the JSON encoding of this page, which is available via the ""Info"" sub-page of this zettel: 

* [[//v/00001012920503?_enc=zjson&_part=zettel]],
* [[//v/00001012920503?_enc=zjson&_part=meta]],
* [[//v/00001012920503?_enc=zjson&_part=content]].
* [[//v/00001012920503?_enc=djson&_part=zettel]],
* [[//v/00001012920503?_enc=djson&_part=meta]],
* [[//v/00001012920503?_enc=djson&_part=content]].

If transferred via HTTP, the content type will be ''application/json''.

A full zettel encoding results in a JSON object with two keys: ''"meta"'' and ''"content"''.
Both values are the same as if you have requested just the appropriate [[part|00001012920800]].

TODO: detailed description.
=== Encoding of metadata
Metadata encoding results in a JSON object, where each metadata key is mapped to the same JSON object name.
The associated value is itself a JSON object with two names.
The first name ``""`` references the [[metadata key type|00001006030000]].
Depending on the key type, the other name denotes the value of the metadata element.
The meaning of these names is [[well defined|00001012920582]], as well as the [[mapping of key types to used object names|00001012920584]].

=== Encoding of zettel content
The content encoding results in a JSON array of objects, where each objects represents a Zettelmarkup element.

Every [!zettelmarkup|Zettelmarkup] element is encoded as a JSON object.
These objects always contain the empty name ''""'' with a string value describing the type of Zettelmarkup element.
Depending on the type, other one letter names denotes the details of the element.
The meaning of these names is [[well defined|00001012920588]].

id: 00001012920582
title: ZJSON Encoding: List of Valid Metadata Value Objects Names
role: manual
tags: #api #manual #reference #zettelstore
syntax: zmk
modified: 20220223184324

Every Metadata value element is mapped to a JSON object with some well defined names / keys.

|=Name | JSON Value | Meaning
| ''"\"'' | string | The type of the Zettelmarkup element.
| ''"i"'' | array  | A sequence of [[inline-structured|00001007040000]] elements.
| ''"s"'' | string | The first / major string value of an element.
| ''"y"'' | array  | A set of string values.

id: 00001012920584
title: ZJSON Encoding: Mapping of Metadata Key Types to Object Names
role: manual
tags: #api #manual #reference #zettelstore
syntax: zmk
modified: 20220304114135

Every [[Metadata key|00001006030000]] is mapped to an [[object name|00001012920582]] where its value is encoded.

|=Type | JSON Object Name | Remark
| [[Credential|00001006031000]] | ''"s"'' | A string with the decrypted credential.
| [[EString|00001006031500]] | ''"s"'' | A possibly empty string.
| [[Identifier|00001006032000]] | ''"s"'' | A string containing a [[zettel identifier|00001006050000]].
| [[IdentifierSet|00001006032500]] | ''"y"'' | An array of strings containing [[zettel identifier|00001006050000]].
| [[Number|00001006033000]] | ''"s"'' | A string containing a numeric value.
| [[String|00001006033500]] | ''"s"'' | A non-empty string.
| [[TagSet|00001006034000]] | ''"y"'' | An array of string containing zettel tags.
| [[Timestamp|00001006034500]] | ''"s"''  | A string containing a timestamp in the format YYYYMMDDHHmmSS.
| [[URL|00001006035000]] | ''"s"'' | A string containing an URL.
| [[Word|00001006035500]] | ''"s"'' | A string containing a word (no space characters)
| [[WordSet|00001006036000]] | ''"y"'' | An array of strings containing words.
| [[Zettelmarkup|00001006036500]] | ''"i"'' | A sequence of [[inline-structured|00001007040000]] elements.

Please note, that metadata is weakly typed.
Every metadata key expects a certain type.
But the user is free to enter something different.
For example, even if the metadata type is ""number"", its value could still be ""abc"".
However, the mapping itself is always valid.

id: 00001012920588
title: ZJSON Encoding: List of Valid Zettelmarkup Element Objects Names
role: manual
tags: #api #manual #reference #zettelstore
syntax: zmk
modified: 20220301102447

Every [[Zettelmarkup|00001007000000]] element is mapped to a JSON object with some well defined names / keys.

|=Name | JSON Value | Meaning
| ''"\"'' | string | The type of the Zettelmarkup element.
| ''"a"'' | object | Additional attributes of the element.
| ''"b"'' | array  | A sequence of [[block-structured|00001007030000]] elements.
| ''"c"'' | array  | A sequence of a sequence of (sub-) list elements or [[inline-structured|00001007040000]] elements. Used for nested lists.
| ''"d"'' | array  | A sequence of description list elements, where each element is an object of a definition term and a list of descriptions.
| ''"e"'' | array  | A sequence of descriptions: a JSON array of simple description, which is itself a JSON array of block structured elements.
| ''"i"'' | array  | A sequence of [[inline-structured|00001007040000]] elements.
| ''"j"'' | object | An objects describing a BLOB element.
| ''"n"'' | number | A numeric value, e.g. for specifying the [[heading|00001007030300]] level.
| ''"o"'' | string | A base64 encoded binary value. Used in some BLOB elements.
| ''"p"'' | array  | A sequence of two elements: a sequence of [[table|00001007031000]] header value, followed by a sequence of sequence of table row values.
| ''"q"'' | string | A second string value, if ''""s""'' is already used.
| ''"s"'' | string | The first / major string value of an element.
| ''"v"'' | string | A third string value, if ''""q""'' is already used.

id: 00001012920800
title: Values to specify zettel parts
role: manual
tags: #api #manual #reference #zettelstore
syntax: zmk
modified: 20220214175335
modified: 20210727125306

When working with [[zettel|00001006000000]], you could work with the whole zettel, with its metadata, or with its content:
; [!zettel|''zettel'']
; [!zettel]''zettel''
: Specifies that you work with a zettel as a whole.
  Contains identifier, metadata, and content of a zettel.
; [!meta|''meta'']
; [!meta]''meta''
: Specifies that you only want to cope with the metadata of a zettel.
  Contains identifier and metadata of a zettel.
; [!content|''content'']
; [!content]''content''
: Specifies that you are only interested in the zettel content.
  Contains identifier and content of a zettel.

id: 00001018000000
title: Troubleshooting
role: zettel
tags: #manual #zettelstore
syntax: zmk
modified: 20220218125940
modified: 20220119140045

This page lists some problems and their solutions that may occur when using your Zettelstore.

=== Installation
* **Problem:** When you double-click on the Zettelstore executable icon, macOS complains that Zettelstore is an application from an unknown developer.
  Therefore, it will not start Zettelstore.
** **Solution:** Press the ''Ctrl'' key while opening the context menu of the Zettelstore executable with a right-click.
** **Solution:** Press the ++Ctrl++ while opening the context menu of the Zettelstore executable with a right-click.
   A dialog is then opened where you can acknowledge that you understand the possible risks when you start Zettelstore.
   This dialog is only resented once for a given Zettelstore executable.
* **Problem:** When you double-click on the Zettelstore executable icon, Windows complains that Zettelstore is an application from an unknown developer.
** **Solution:** Windows displays a dialog where you can acknowledge possible risks and allows to start Zettelstore.

=== Authentication
* **Problem:** [[Authentication is enabled|00001010040100]] for a local running Zettelstore and there is a valid [[user zettel|00001010040200]] for the owner.
  But entering user name and password at the [[web user interface|00001014000000]] seems to be ignored, while entering a wrong password will result in an error message.
** **Explanation:** A local running Zettelstore typically means, that you are accessing the Zettelstore using an URL with schema ''http://'', and not ''https://'', for example ''http://localhost:23123''.
   The difference between these two is the missing encryption of user name / password and for the answer of the Zettelstore if you use the ''http://'' schema.
** **Explanation:** A local running Zettelstore typically means, that you are accessing the Zettelstore using an URL with schema ''http:/\/'', and not ''http**s**:/\/'', for example ''http:/\/localhost:23123''.
   The difference between these two is the missing encryption of user name / password and for the answer of the Zettelstore if you use the ''http:/\/'' schema.
   To be secure by default, the Zettelstore will not work in an insecure environment.
** **Solution 1:** If you are sure that your communication medium is safe, even if you use the ''http:/\/'' schema (for example, you are running the Zettelstore on the same computer you are working on, or if the Zettelstore is running on a computer in your protected local network), then you could add the entry ''insecure-cookie: true'' in you [[startup configuration|00001004010000#insecure-cookie]] file.
** **Solution 2:** If you are not sure about the security of your communication medium (for example, if unknown persons might use your local network), then you should run an [[external server|00001010090100]] in front of your Zettelstore to enable the use of the ''https://'' schema.
** **Solution 2:** If you are not sure about the security of your communication medium (for example, if unknown persons might use your local network), then you should run an [[external server|00001010090100]] in front of your Zettelstore to enable the use of the ''http**s**:/\/'' schema.

}

// NewContent creates a new content from a string.
func NewContent(data []byte) Content {
	return Content{data: data, isBinary: calcIsBinary(data)}
}

// Length returns the number of bytes stored.
func (zc *Content) Length() int { return len(zc.data) }

// Equal compares two content values.
func (zc *Content) Equal(o *Content) bool {
	if zc == nil {
		return o == nil
	}
	if zc.isBinary != o.isBinary {
		return false

	registerKey(api.KeyCredential, TypeCredential, usageUser, "")
	registerKey(api.KeyDead, TypeIDSet, usageProperty, "")
	registerKey(api.KeyFolge, TypeIDSet, usageProperty, "")
	registerKey(api.KeyForward, TypeIDSet, usageProperty, "")
	registerKey(api.KeyLang, TypeWord, usageUser, "")
	registerKey(api.KeyLicense, TypeEmpty, usageUser, "")
	registerKey(api.KeyModified, TypeTimestamp, usageComputed, "")
	registerKey(api.KeyNoIndex, TypeBool, usageUser, "")
	registerKey(api.KeyPrecursor, TypeIDSet, usageUser, api.KeyFolge)
	registerKey(api.KeyPublished, TypeTimestamp, usageProperty, "")
	registerKey(api.KeyReadOnly, TypeWord, usageUser, "")
	registerKey(api.KeySummary, TypeZettelmarkup, usageUser, "")
	registerKey(api.KeyURL, TypeURL, usageUser, "")
	registerKey(api.KeyUselessFiles, TypeString, usageProperty, "")
	registerKey(api.KeyUserID, TypeWord, usageUser, "")

	pairs := make(map[string]string, len(data))
	for k, v := range data {
		pairs[k] = v
	}
	return &Meta{Zid: zid, pairs: pairs}
}

// Length returns the number of bytes stored for the metadata.
func (m *Meta) Length() int {
	if m == nil {
		return 0
	}
	result := 6 // storage needed for Zid
	for k, v := range m.pairs {
		result += len(k) + len(v) + 1 // 1 because separator
	}
	return result
}

// Clone returns a new copy of the metadata.
func (m *Meta) Clone() *Meta {
	return &Meta{
		Zid:     m.Zid,
		pairs:   m.Map(),
		YamlSep: m.YamlSep,
	}

import (
	"strconv"
	"strings"
	"sync"
	"time"

	"zettelstore.de/c/api"
	"zettelstore.de/c/zjson"
)

// DescriptionType is a description of a specific key type.
type DescriptionType struct {
	Name  string
	IsSet bool
}

	t := &DescriptionType{name, isSet}
	registeredTypes[name] = t
	return t
}

// Supported key types.
var (
	TypeBool         = registerType("Boolean", false)
	TypeCredential   = registerType(zjson.MetaCredential, false)
	TypeEmpty        = registerType(zjson.MetaEmpty, false)
	TypeID           = registerType(zjson.MetaID, false)
	TypeIDSet        = registerType(zjson.MetaIDSet, true)
	TypeNumber       = registerType(zjson.MetaNumber, false)
	TypeString       = registerType(zjson.MetaString, false)
	TypeTagSet       = registerType(zjson.MetaTagSet, true)
	TypeTimestamp    = registerType(zjson.MetaTimestamp, false)
	TypeURL          = registerType(zjson.MetaURL, false)
	TypeWord         = registerType(zjson.MetaWord, false)
	TypeWordSet      = registerType(zjson.MetaWordSet, true)
	TypeZettelmarkup = registerType(zjson.MetaZettelmarkup, false)
	TypeCredential   = registerType("Credential", false)
	TypeEmpty        = registerType("EString", false)
	TypeID           = registerType("Identifier", false)
	TypeIDSet        = registerType("IdentifierSet", true)
	TypeNumber       = registerType("Number", false)
	TypeString       = registerType("String", false)
	TypeTagSet       = registerType("TagSet", true)
	TypeTimestamp    = registerType("Timestamp", false)
	TypeURL          = registerType("URL", false)
	TypeWord         = registerType("Word", false)
	TypeWordSet      = registerType("WordSet", true)
	TypeZettelmarkup = registerType("Zettelmarkup", false)
)

// Type returns a type hint for the given key. If no type hint is specified,
// TypeUnknown is returned.
func (*Meta) Type(key string) *DescriptionType {
	return Type(key)
}

var (
	cachedTypedKeys = make(map[string]*DescriptionType)
	mxTypedKey      sync.RWMutex
	suffixTypes     = map[string]*DescriptionType{
		"-number": TypeNumber,
		"-role":   TypeWord,
		"-set":    TypeWordSet,
		"-title":  TypeZettelmarkup,
		"-url":    TypeURL,
		"-zettel": TypeID,
		"-zid":    TypeID,
		"-zids":   TypeIDSet,
	}
)

// Type returns a type hint for the given key. If no type hint is specified,
// TypeEmpty is returned.
func Type(key string) *DescriptionType {
	if k, ok := registeredKeys[key]; ok {

//-----------------------------------------------------------------------------
// Copyright (c) 2020-2022 Detlef Stern
// Copyright (c) 2020-2021 Detlef Stern
//
// This file is part of Zettelstore.
// This file is part of zettelstore.
//
// Zettelstore is licensed under the latest version of the EUPL (European Union
// Public License). Please see file LICENSE.txt for your rights and obligations
// under this license.
//-----------------------------------------------------------------------------

// Package domain provides domain specific types, constants, and functions.
package domain

import (
import "zettelstore.de/z/domain/meta"
	"zettelstore.de/z/domain/meta"
)

// Zettel is the main data object of a zettelstore.
type Zettel struct {
	Meta    *meta.Meta // Some additional meta-data.
	Content Content    // The content of the zettel itself.
}

// Length returns the number of bytes to store the zettel (in a domain view,
// not in a technical view).
func (z Zettel) Length() int { return z.Meta.Length() + z.Content.Length() }

// Equal compares two zettel for equality.
func (z Zettel) Equal(o Zettel, allowComputed bool) bool {
	return z.Meta.Equal(o.Meta, allowComputed) && z.Content.Equal(&o.Content)
}

//-----------------------------------------------------------------------------
// Copyright (c) 2020-2021 Detlef Stern
//
// This file is part of zettelstore.
//
// Zettelstore is licensed under the latest version of the EUPL (European Union
// Public License). Please see file LICENSE.txt for your rights and obligations
// under this license.
//-----------------------------------------------------------------------------

// Package encoder provides a generic interface to encode the abstract syntax
// tree into some text form.
package encoder

import (
	"encoding/base64"
	"io"
)

// BufWriter is a specialized buffered writer for encoding zettel.
type BufWriter struct {
	w      io.Writer // The io.Writer to write to
	err    error     // Collect error
	length int       // Sum length
	buf    []byte    // Buffer to collect bytes
}

// NewBufWriter creates a new BufWriter
func NewBufWriter(w io.Writer) BufWriter {
	return BufWriter{w: w, buf: make([]byte, 0, 4096)}
}

// Write writes the contents of p into the buffer.
func (w *BufWriter) Write(p []byte) (int, error) {
	if w.err != nil {
		return 0, w.err
	}
	w.buf = append(w.buf, p...)
	if len(w.buf) > 2048 {
		w.flush()
		if w.err != nil {
			return 0, w.err
		}
	}
	return len(p), nil
}

// WriteString writes the contents of s into the buffer.
func (w *BufWriter) WriteString(s string) {
	if w.err != nil {
		return
	}
	w.buf = append(w.buf, s...)
	if len(w.buf) > 2048 {
		w.flush()
	}
}

// WriteStrings writes the contents of sl into the buffer.
func (w *BufWriter) WriteStrings(sl ...string) {
	for _, s := range sl {
		w.WriteString(s)
	}
}

// WriteByte writes the content of b into the buffer.
func (w *BufWriter) WriteByte(b byte) error {
	w.buf = append(w.buf, b)
	return nil
}

// WriteBytes writes the content of bs into the buffer.
func (w *BufWriter) WriteBytes(bs ...byte) {
	w.buf = append(w.buf, bs...)
}

// WriteBase64 writes the content of p into the buffer, encoded with base64.
func (w *BufWriter) WriteBase64(p []byte) {
	if w.err == nil {
		w.flush()
	}
	if w.err == nil {
		encoder := base64.NewEncoder(base64.StdEncoding, w.w)
		length, err := encoder.Write(p)
		w.length += length
		err1 := encoder.Close()
		if err == nil {
			w.err = err1
		} else {
			w.err = err
		}
	}
}

// Flush writes any buffered data to the underlying io.Writer. It returns the
// number of bytes written and an error if something went wrong.
func (w *BufWriter) Flush() (int, error) {
	if w.err == nil {
		w.flush()
	}
	return w.length, w.err
}

func (w *BufWriter) flush() {
	length, err := w.w.Write(w.buf)
	w.buf = w.buf[:0]
	w.length += length
	w.err = err
}