[TED] XML schema datatypes version 1.0 versus 1.1

I am writing this e-mail in partial fulfillment of action 369 and to
report on the status of the XML schema datatype version reference problem.

Background of the problem:
For the purpose of reusing existing web standards we have decided in RIF
(following RDF/OWL) to use XML schema built-in datatypes, where
possible, for the representation of concrete values (e.g. strings,
integers, dates).
There are, however, versions of XML schema datatypes.  Version 1.0 is a
recommendation since 2004 [1]; it is based, to a large extent, on XML
1.0 (e.g. the lexical space of the xsd:string datatype is based on the
characters allowed in XML 1.0).  Version 1.1 is currently a working
draft [2]; it is based on XML 1.1, rather than 1.0, but still allows to
use the datatypes with XML 1.0.
Now, in order to make sure that RIF is well defined we have to decide
which datatypes to use, version 1.0 or 1.1.
Since there was not enough XML schema expertise in RIF working group, I
asked the XML schema working group what the differences are and which
version we should use.  [3]

Response from the XML schema working group:
The working group replied [4] that the two main differences are that:
- XML schema 1.1 datatypes are less restrictive; several more characters
are allowed to be used, and the XML schema 1.0 specification can
potentially be read as disallowing the use of the language with XML 1.1
- the specification has been cleaned up, several errors have been
corrected, and newer versions of external specifications (e.g. RFCs) are
referenced

Based on these two improvements the author of the reply suggested that
we use version 1.1.  However, this is not the official position of the
working group.

Next steps:
We basically need to decide which version of XML schema datatypes we
refer to; 1.0 [1] or 1.1 [2].
Because the quality of the 1.1 specification is higher than that of the
1.0 specification, and because there seems to be no technical reason for
choosing 1.0, referring to version 1.1 seems to be the best choice.
However, because it is merely a (although last call) working draft and
not a recommendation (i.e. it has no "stamp of approval" from W3C), it
might be problematic to use 1.1 (especially when going to last call and
beyond).

I would propose to use version 1.0 as long as it is not a
recommendation, but explicitly state in our document that we will change
to version 1.1 if it reaches recommendation status before we do.

Best, Jos

[1] http://www.w3.org/TR/xmlschema-2/
[2] http://www.w3.org/TR/xmlschema11-2/
[3]
http://lists.w3.org/Archives/Public/www-xml-schema-comments/2007JulSep/0089.html
[4]
http://lists.w3.org/Archives/Public/www-xml-schema-comments/2007OctDec/0097.html