[Bug 9840] [XSLT 2.0] xsl:number level="single" has different behaviour to XSLT 1.0


--- Comment #1 from Michael Kay <mike@saxonica.com>  2010-06-03 13:26:07 ---
After this length of time, it's difficult to remember all the details of the
reasoning that went into this. I know we spent a lot of time trying to
understand exactly what the XSLT 1.0 spec was trying to say, and filling the
gaps when it seemed incomplete or inconsistent.

The first problem with the 1.0 text is that it says nothing about what happens
when there is no ancestor node that matches the from pattern - which doesn't
affect this case, but affected a lot of the thinking about how to rewrite the
rule. The second problem is that some uses of "ancestor" in this sentence -
notably the first one "that ancestor" - only make sense if read as
ancestor-or-self; and presumably we decided this was also the intended reading
in the phrase "descendants of the nearest ancestor that matches the from

Generally we took the view that xsl:number was sufficiently under-specified in
corner cases that we could afford to be a little cavalier about compatibility.
In some cases (see bug #5849 for one example that arose after the Rec was
published - there were other cases during spec development) we took the trouble
to investigate behaviour of existing implementations, and found that it was
highly variable.

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Received on Thursday, 3 June 2010 13:26:09 UTC