We've made a very minor change to the MODS version 2 schema,
http://www.loc.gov/standards/mods/v2/mods-2.xsd

 The following import was in the original MODS 2 schema:

<xsd:import namespace="http://www.w3.org/TR/xlink"
schemaLocation="http://www.loc.gov/standards/mets/xlink.xsd"/>

and is replaced by:

  <xsd:import namespace="http://www.w3.org/TR/xlink"
schemaLocation="http://www.loc.gov/standards/mets/version13/xlink.xsd" />

i.e. the xlink schema location is changed, but not the namespace.

The reason is that in future versions  (e.g. 3) the xlink namespace changes,
and the schema at the location  previously cited also changes to match the
new namespace.  Thus this schema would not validate, with the old xlink
namespace
and new xlink schema.  The old namspace is retained, and the schema location
is changed to the location of the archived old version.

This change was requested by a MODS user because MODS 2 records would not
validate with this mis-match. Hopefully that solves the problem.

--Ray Denenberg