A reference is encoded as the actual reference value, and a symbol describing the state of that actual reference value.
Reference = ( ReferenceState String ).
The string contains the actual reference value.
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.
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.