NXobject: add W3ID to identifier type

Author: woutdenolf

base_classes/NXobject.nxdl.xml

@@ -192,6 +192,18 @@
 						Example: https://purl.org/dc/elements/1.1/title
 					</doc>
 				</item>
+				<item value="W3ID">
+					<doc>
+						A w3id is a persistent HTTP URI provided via the w3id.org service,
+						operated by the W3C Permanent Identifier Community Group.
+
+						It is implemented as a permanent, managed redirect, typically used
+						for vocabularies, ontologies, Linked Data resources, and research artifacts.
+
+						Syntax: https://w3id.org/{path}
+						Example: https://w3id.org/example/resource
+					</doc>
+				</item>
 				<item value="ROR">
 					<doc>
 						Research Organization Registry