A reference is encoded as the actual reference value, and a symbol describing the state of that actual reference value.
:::{="syntax"}
__Reference__ **=** ''('' __ReferenceState__ String '')''.
:::
The string contains the actual reference value.
:::{="syntax"}
__ReferenceState__ **=** ''INVALID'' **|** ''ZETTEL'' **|** ''SELF'' **|** ''FOUND'' **|** ''BROKEN'' **|** ''HOSTED'' **|** ''BASED'' **|** ''QUERY'' **|** ''EXTERNAL''.
:::
The meaning of the state symbols corresponds to that of the symbols used for the description of [[link references|00001012931600#link]].
; ''INVALID''
: The reference value is invalid.
; ''ZETTEL''
: The reference value is a reference to a zettel.
This value is only possible before evaluating the zettel.
; ''SELF''
: The reference value is a reference to the same zettel, to a specific mark.
; ''FOUND''
: The reference value is a valid reference to an existing zettel.
This value is only possible after evaluating the zettel.
; ''BROKEN''
: The reference value is a valid reference to an missing zettel.
This value is only possible after evaluating the zettel.
; ''HOSTED''
: The reference value starts with one slash character, denoting an absolute local reference.
; ''BASED''
: The reference value starts with two slash characters, denoting a local reference interpreted relative to the Zettelstore base URL.
; ''QUERY''
: The reference value contains a query expression.
; ''EXTERNAL''
: The reference value contains a full URL, referencing a resource outside of the Zettelstore server.