Children of link reference.
Optional dataData associated with the mdast link reference.
Relation of association.
identifier is a source value: character escapes and character
references are not parsed.
It can match another node.
Its value must be normalized.
To normalize a value, collapse markdown whitespace ([\t\n\r ]+) to a space,
trim the optional initial and/or final space, and perform Unicode-aware
case-folding.
Optional labelOptional positionPosition of a node in a source document.
Nodes that are generated (not in the original source document) must not have a position.
Explicitness of the reference.
Node type of mdast link reference.
Markdown link reference.