Date: Sat, 8 May 2010 07:48:25 -0400
From: "Costello, Roger L."<costello@xxxxxxxxx>
[...]
Where does xsl:apply-templates reside within the field of programming?

I think that the closest analogy is a map in Prolog where templates
are considered Horn clauses of a single binary relation "template":

template(...,...) :- ... .  % One for each xsl:template
...

apply_template([],[]).
apply_template([X|P],[Y|Q]) :- template(X,Y), apply_template(P,Q).