The xml.xsd question is more easily answered. Several years ago we were
forced to find a way to reduce the number of MODS accesses to the W3C
server. The reason was that W3C was complaining (loudly) about excessive
accesses and threatening to block certain clients. Someone was not properly
caching xml.xsd and was in addition validating an inordinate number of MODS
records. This happened a number of times, we were unsuccessful at tracking
down the culprit, and as a quick fix changed the reference to LC rather than
W3C, and the problem has not resurfaced.
Xlink is more complicated, although you could use the same justification,
even if there weren't additional complications. In the Xlink case, the W3C
version simply didn't meet MODS requirements. I can't recall exactly why,
I'm tracking that down, and I'll get back to you (but I wanted to respond
quickly to the question).
> -----Original Message-----
> From: Metadata Object Description Schema List
> [mailto:[log in to unmask]] On Behalf Of Wolfgang Koller
> Sent: Monday, March 21, 2011 4:53 AM
> To: [log in to unmask]
> Subject: [MODS] Problems with Import(s)
> Dear all,
> I'm currently working on a schema which uses MODS to track the
> bibliographic information of an element.
> However, unfortunately, there are several critical imports in MODS
> which heavily conflict with other schema which try to import into the
> same namespace (multiple definitions of the same attributes / elements).
> Unfortunately MODS uses its own copy of the xml.xsd schema and the
> xlink.xsd schema.
> - As far as I found out, the xlink schema is a separate & modified
> version of the original xlink schema which can be found at
> http://www.w3.org/1999/xlink.xsd. However from my point of view, it is
> heavily dangerous to customize a schema but import it into the same
> namespace then. I would recommend defining a own namespace for your
> custom schemas (even if they are based on an "official" schema).
> - The same applies for the xml.xsd schema (the official version can be
> found at http://www.w3.org/2001/xml.xsd). However there I did not find
> any difference in the official and the version hosted by loc - what's
> the reason for hosting it own your own?
> Is there any chance that you are going to update mods and reference the
> official schemas and/or change the target namespace so that mods can be
> combined with others schemas trying to import the official ones?
> Best wishes,
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