id

The primary identifier in the external database of the object to which this xref refers.

Source:http://www.biopax.org/release/biopax-level3.owl#id

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
rdfs:comment
The primary identifier in the external database of the object to which this xref refers.@en, The primary identifier in the external database of the object to which this xref refers.@en, The primary identifier in the external database of the object to which this xref refers.@en
rdfs:range
rdfs:domain