Mike wrote:
>> I agree that you can think of the pertinent aspects of the focus as
>> being an additional argument to the function. I just wanted to
>> bring out the point because the only exising built-in function that
>> returns a node tree - document() - returns the same tree *across
>> the stylesheet* rather than *in a particular context*.
>
> Actually the result of document() is context dependent, and in a
> rather unusual way: it is the only construct whose result depends on
> the base URI of the stylesheet element containing the expression.
> This base URI is used to expand any relative URI in the call.

Ahh, good point. There are also functions that rely on what's been
defined in the stylesheet:

  - key() uses xsl:key
  - format-number() uses xsl:decimal-format
  - sort() uses xsl:sort-key (introduced in XSLT 2.0)

You could easily imagine user and vendor-defined extension functions
that similarly relied on data elements in the stylesheet.

Fortunately, given a particular stylesheet in a particular location,
none of this impacts on what the functions will return for a
particular set of arguments. So you can guarantee that it doesn't
change during the lifetime of the transformation (well, assuming that
no vendor-defined extension functions mess around with the stylesheet
itself during processing, that is!).

Cheers,

Jeni

---
Jeni Tennison
http://www.jenitennison.com/


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