While I'm not a fan of EXSL, I feel offended for them -- they never
intended to propose extension functions for incrementing an
xsl:variable -- or am I wrong Jeny?

Incrementing a variable is not a non-XSLT problem due to two reasons:

1. It is not "non-XSLT" XSLT -- programmers write nice programs while
still being able to have the right values in the right xsl:variables

2. It is not a problem.

On should first learn XSLT, and only after achieving some experience
and understanding try to avoid raising non-existing problems.

Remember: if you consider the inability to increment a xsl:variable a
problem, this means 100% that you do not have proper basic experience
and understanding of XSLT. If this is the case, the best way is to
study -- read a good book (e.g. Mike Kay's "XSLT Programmer's
Reference"), study a few XSLT FAQs (Dave Pawson's is the most extensive
one).

--
Petr Cimprich
Ginger Alliance
www.gingerall.com