title: Data Encoding role: manual tags: #api #manual #reference #zettelstore syntax: zmk back: 00001012920500 backward: 00001012920500 box-number: 1 copyright: (c) 2020-present by Detlef Stern created: 20260303142542 forward: 00001012920516 00001012921200 00001012930000 lang: en license: EUPL-1.2-or-later modified: 20260612162702 published: 20260612162702 visibility: public The data encoding represents the zettel as a special [symbolic expression](00001012930000). In contrast to the similar-looking [sz encoding](00001012920516), a much simpler structure is used. If transferred via HTTP, the content type will be `text/plain; charset=utf-8`. A full zettel, both metadata and content, is encoded by the list `(zettel` [*Metadata*](#metadata) [*Access rights*](#access-rights) [*Content encoding*](#content-encoding) [*Content*](#content) `)`. If you only want to encode the metadata of a zettel, the following format will be used: `(list` [*Metadata*](#metadata) [*Access rights*](#access-rights) `)`. # Metadata Metadata is basically a sequence of key / value pairs: *Metadata* __=__ `(meta` `(` *Key* *Value* `)` … `)`.*Key* __=__ Symbol.*Value* __=__ String. Each *Key* is a symbol, derived from the metadata key. The *Value* is a string containing the value of the corresponding metadata entry. # Access rights This element encodes [access rights](00001012921200) of a zettel: *Access rights* __=__ `(rights` Number `)`. # Content encoding The content encoding specifies, how the zettel content is encoded. Currently, two values are supported: the empty string and the string `"base64"`. *Content encoding* __=__ `(encoding "")` __|__ `(encoding "base64")`. The empty string indicates that the content is not encoded and can be used as is. `"base64"` indicates that the content string is Base64-encoded (typically used for binary content). # Content The content of a zettel is always encoded as a readable string. For binary content, it is first encoded using Base64. *Content* __=__ `(content` String `)`.