The XSL Working Group needs your help to try out a test case.
Another case has been discovered of a situation where the XSLT 2.0 rules
for xsl:number appear to be unintentionally incompatible with the XSLT
1.0 rules. The last time this arose, it was an edge case and we found
that XSLT 1.0 processors showed no uniformity at all in the way it was
handled. This time, it seems to be less of an edge case, and it might be
that it hasn't been noticed until now because Saxon and some other 2.0
processors are actually following the XSLT 1.0 rules.
Consider this source document:
<doc>
<a>
<title/>
</a>
</doc>
and this stylesheet:
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform";>
<xsl:template match="/">
<out>
<xsl:for-each select="//title">
<xsl:number from="a" count="a" level="single"/>
</xsl:for-each>
</out>
</xsl:template>
</xsl:stylesheet>
The XSLT 2.0 specification is explicit that the result should be
<out>1</out>
The XSLT 1.0 specification is not quite so clear-cut, but the simplest
reading of it is to produce the result <out/>, which is what both Saxon
9.x and Saxon 6.5.5 produce. But we know of other XSLT 2.0
implementations that correctly follow the 2.0 specification.
The Working Group, before deciding whether to issue an erratum to XSLT
2.0 to change the behaviour to match XSLT 1.0, is interested to know how
existing implementations (both 1.0 and 2.0) handle this. If you could
try the above stylesheet on your favourite 1.0 or 2.0 processor and
submit the results, I will collate them. Thank you for your assistance.
In practice, using the from attribute with level="single" isn't very
useful, so it may not make much practical difference what we decide. But
if XSLT 1.0 processors are showing consistent results, this will add
weight to the argument in favour of changing 2.0 to be compatible.
Michael Kay
on behalf of the XSL Working Group