Subject: [LC response] To Marko Luther
Thank you for your comment
on the OWL 2 Web Ontology Language last call drafts.
As you rightly point out, the current writing of prefix names in the examples of the Primer conforms to the technical specification of the OWL/XML syntax  and thus is correct. Changing the OWL/XML serialisation to require colons at this point would be a non-editorial change that affects implementations, so the Working Group has decided against this change.
However, it is true that different syntactic conventions in different serialisations might be a source of confusion, and we therefore have added an explicit remark to point out this difference in the respective section of the Primer. See  for a diff.
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I got confused by the examples given in the PR OWL 2 Primer at <http://www.w3.org/TR/2009/PR-owl2-primer-20090922/> regarding the exact syntax for prefix names. According to the PR OWL 2 Structural Specification at <http://www.w3.org/TR/2009/PR-owl2-syntax-20090922/#IRIs> the last character should always be a colon (see also the PNAME_NS production in <http://www.w3.org/TR/2008/REC-rdf-sparql-query-20080115/ >). This is also the case for all examples given in Functional Style Syntax, e.g. those in <http://www.w3.org/TR/2009/PR-owl2-primer-20090922/#Appendix:_The_Complete_Sample_Ontology > Prefix(:=<http://example.com/owl/families/>) Prefix(otherOnt:=<http://example.org/otherOntologies/families/>) Prefix(xsd:=<http://www.w3.org/2001/XMLSchema#>) Prefix(owl:=<http://www.w3.org/2002/07/owl#>) .. However, the corresponding example in OWL/XML Syntax has the following entry <Prefix name="otherOnt" IRI="http://example.org/otherOntologies/families/ "/> which complies with the OWL 2 XML Schema. Note that here the name of the prefix does not contain a colon. I would have expected the following: <Prefix name="otherOnt:" IRI="http://example.org/otherOntologies/families/ "/> What is the correct way to specify a prefix in OWL/XML Syntax? Would the empty prefix be defined with name="" or name=":"? Best regards, Marko Luther