RE: Request clarification/erratum regarding "from" in xsl:number

We have attempted a formalization of the rules in the XSLT 2.0 draft. These
rules were orginally written to reflect my interpretation of the XSLT 1.0
rules; if the WG decided to issue a clarification on the XSLT 1.0 rules, I
think it would be likely to follow what we have published for XSLT 2.0.

You are quite correct to point out that the XSLT 1.0 formulation is
problematic.

Michael Kay



> -----Original Message-----
> From: David Marston/Cambridge/IBM [mailto:david_marston@us.ibm.com] 
> Sent: 25 October 2002 21:04
> To: xsl-editors@w3.org
> Cc: xslt-conformance@lists.oasis-open.org
> Subject: Request clarification/erratum regarding "from" in xsl:number
> 
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> These questions are submitted on behalf of the XSLT/Xpath 
> Conformance Technical Committee (TC). We had a detailed 
> technical discussion at our September teleconference and 
> concluded that we don't all agree about the meaning of the 
> XSLT 1.0 Rec, as amended by errata up through E34. Since we 
> will accept or reject test cases based on the meaning, we 
> need a normative statement. If there will be a time lag 
> before the normative statement, we can use our "gray area" 
> mechanism while the statement is prepared for publication, as 
> long as we know what its substance will be.
> 
> Regarding xsl:number, counting is reasonably clear except 
> when the from attribute is specified. Erratum E23 addresses one case.
> 
> What do you do if the from attribute is set to a node name 
> that has not yet been encountered? Several Xalan numbering 
> tests exemplify this issue, with numbering61 being the 
> simplest example for level="any".
> 
> Erratum E23 addresses this situation (only for level="any") 
> but leaves the sentence: "If the from attribute is specified, 
> then only nodes after the first node before the current node 
> that match the from pattern are considered." It does not say 
> "only nodes after the nearest previous
> (preceding|ancestor-or-self) occurrence of a node matching 
> the from pattern" are considered, and there is a possible 
> interpretation that counting prior to the first from-node can 
> proceed as normal. In other words, each from-node resets the 
> counter but you can start counting without one. Nodes that 
> "match the from pattern" are not considered for counting per 
> se (but see below), but rather define the range of nodes over 
> which scanning for countable nodes will take place. But does 
> lack of a from-node (so far) mean no range?
> 
> For the other kinds of level, there is no erratum to date. 
> See the Xalan test numbering20 for level="single" and 
> numbering19 for level="multiple", neither having count 
> specified. 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, the main concern is for 
> level="multiple", which has the same sentence about from, 
> with <D> and <E> in it. Two questions arise.
> 
> Larger question: does the lack of an ancestor(-or-self?) 
> matching the from pattern mean (1) do what you do for an 
> empty list, (2) put out no characters because the xsl:number 
> instruction is moot, or (3) number as usual because the 
> from-node is a reset to the counter?
> 
> Smaller question: what should be done when a node matches 
> both from and count? (See Xalan test numbering63, which has 
> <xsl:number level="single" from="a" count="a|b|c|d|e" 
> format="1"/> in the stylesheet and has <a> elements in its 
> input data.) Referring back to the quote from the spec, note 
> the word "descendants" rather than "elements on the 
> descendant-or-self axis" between <D> and <E>. That's the 
> difference between a count of 0 and 1 when an <a> is encountered.
> 
> In summary, we want to know the prescribed counting result 
> before the first occurrence of a from-node, and when the 
> count-node is also the from-node. If the level attribute 
> makes a difference, we want to know the required behavior for 
> each kind of level. .................David Marston
>

Received on Sunday, 27 October 2002 09:03:29 UTC