[xslt-conformance] xsl:number issue: from not yet encountered whenlevel is single or multiple

[David Marston/Cambridge/IBM <david_marston@us.ibm.com>]

In a previous note, I discussed the issue about counting nodes before
the first occurrence of a node matching the from pattern, in the case
where level="any", which case was clarified [sic] by an erratum. For
the other kinds of level, apparently the WG thought the verbiage was
sufficiently clear. See the Xalan test numbering20 for level="single"
and numbering19 for level="multiple", neither having count specified.

Consider numbering20, which has
<xsl:number level="single" from="chapter" format="(1) "/>
in a template that matches on <note>, and there are <note> nodes both
inside <chapter> nodes and not. Without a from, we have numbering53,
which is non-controversial, as far as I know.

I will quote the Rec, but insert tags <A>, <B>, etc. for later
reference.
When level="single", it goes up to the <A>first node in the
ancestor-or-self axis that matches the count pattern</A>, and
constructs a list of length one containing one plus the number of
preceding siblings of <B>that ancestor</B> that match the count pattern.
If there is no <C>such ancestor</C>, it constructs an empty list. If
the from attribute is specified, then the only <D>ancestors</D> that are
searched are those that are descendants of the nearest <E>ancestor</E>
that matches the from pattern. Preceding siblings has the same meaning
here as with the preceding-sibling axis.

By the rules of ordinary English, we can deduce that references <B>
and <C> actually mean "node on the ancestor-or-self axis" rather
than simply "ancestor", but what about <D> and <E>? Actually, usage
<E> is probably the same as in another issue presented earlier.

Conversationally, the issue is whether the notes that are not under
<chapter> nodes should be numbered, since the from attribute says to
reset the numbering at each chapter. This might be realistic for
level="multiple" but not for level="single", since you could use a
union (see numbering72) for the latter case.

What do you think, and why?
A) It should be an empty list; higher nodes can't be "searched"
B) It should be 1-n; from does a reset but you can count before it
C) Some other meaning?
D) Must refer this to the XSL WG for resolution

If "empty list" is the answer, there is a separate question about
rendering the number.
.................David Marston