> Thanks for the suggestion!
> I didn't know I could use such a syntax...

It's surprising how many XSLT users don't.
> 
> What do the curly braces exactly mean? Do they reppresent just a
> simple XPath match and substitution in a more readable form?

It's called an "attribute value template". You can write any XPath
expression inside the curlies, and the result of the expression is converted
to a string and included in the attribute value.
> 
> (I use xsltproc to process my XSL transformation... is it a 
> good choice?)
> 

You can't expect me to give an objective answer on that one...

I would say, however, it's worth having more than one XSLT processor in your
kitbag. There will always be times when you're convinced you've found a bug
in your XSLT processor, and running the same transformation on a different
processor will often disabuse you of that theory. If you write something
that has chronically bad performance, running on a different processor will
tell you whether the problem is in your code or in the processor that you're
using. Also, if you don't understand the error messages from one processor,
a different processor may express it in terms that make more sense in your
situation. Finally, it will prevent you from using vendor extensions unless
you have a really good reason to do so, which is generally good practice.

For many people now the big decision is not which XSLT processor to use, but
whether and when to start taking advantage of XSLT 2.0. See recent threads
on that topic.

Michael Kay
http://www.saxonica.com/