This was also discussed two years ago; see <http://listserv.loc.gov/cgi-bin/wa?A1=ind1110&L=mods>.
On Oct 9, 2013, at 3:57 PM, Thomas Scheffler <[log in to unmask]> wrote:
> All v3 mods XML Schema documents include a propritary XLINK XML Schema
> from the Library of Congress
> (http://www.loc.gov/standards/xlink/xlink.xsd), which sadly is
> incompatible to the official copy of W3C
> E.g. attributeGroup simpleAttrs (W3C) is named simpleLink (LOC)
> This is no problem if you embed MODS-Metadata in other LOC-Standards
> like METS documents, which use the same schema.
> But if you have a custom container which uses XLink too and has therefor
> imported the official XLINK Schema the problem starts.
> For one Namespace exactly one XML Schema is loaded. Exactly that one
> that is used at the highes import level (here custom container). At the
> point of importing http://www.loc.gov/standards/mods/v3/mods-3-5.xsd the
> official XLink Schema is already loaded so for mods documents in custom
> builds xlink:simpleLink cannot be resolved and results in validation errors.
> I noticed that the LOC Schema was build in 2004 while the last official
> version is of 2008. But I see no reason why the is a need for a custom
> incompatible copy of the xlink schema anymore.
> It would be great if these issues could be solved somehow - after people
> get paid again. One way - that should be compatible - is to re-edit the
> XML Schema for MODS that it uses the XLink Schema of W3C.
> The other way would require to fork every MODS Schema and use a copy of
> it for validating and doing this alike for every release in the future.
> kind regards,
> Thomas Scheffler
> Thomas Scheffler
> Friedrich-Schiller-Universität Jena
> Thüringer Universitäts- und Landesbibliothek
> Bibliotheksplatz 2
> 07743 Jena
> Phone: ++49 3641 940027
> FAX: ++49 3641 940022