skos:notation optional

8e487d38 · David Maus · 7422c3ae · 8e487d38
Commit 8e487d38 authored 7 years ago by David Maus
--- a/src/schema/vocab.rnc
+++ b/src/schema/vocab.rnc
@@ -27,7 +27,7 @@ skos.Concept =
   element skos:Concept {
      rdfPrimarySubject
    & Label+
-    & skos.notation
+    & skos.notation?
    & skos.inScheme
    & skos.match
    & empty