Core concepts in XSLT

Thanks to all of the folks on this list who have helped answer my somewhat
obtuse questions, I have had an XSLT epiphany this weekend. In particular,
Lars' suggestion to get a copy of Abelson's "wizard book" has helped
tremendously in furthering my understanding of this topic. In particular,
section 1.1.5 on the subsitution model for procedure applications and
Section 3.1.3 on the costs of introducing assignment changed my world-view
completely.

As a result of my epiphany, I've been trying to distill down the essence of
XSLT, and I've come to this observation:

XSLT is about three core concepts

1.	Templates are functions that are free of side effects.
2.	Template rules are either
      a) A named function, or 
      b) A function that declares its intent
3.	Templates allow you to generate output from static and dynamic
content.

What do other folks on this list feel about this observation? Are there
things here that should be changed/removed and are there things that should
be added to this list?

Cheers,
-John


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