> > 
> > I believe I can pick up on the missing elements as soon as I've passed
them
> > by. If I have two sorted trees to compare and in one I go from A to C
and in
> > the other I go from A to B then I know I've missed B in the first?
>
>
> But only if you have some specification of the order other than "the
> order in which they appear". By using "A" and "C" above you are implying
> alphabetic order and so its not hard to spot B is missing but in your
> example 
> you said the order of the elements in the two docs could be different 
> so how in that case do I know B is missing rather than just later in the
> order?

The document order from document A is sufficient.  This document is actually
generated from a database using a sort order as specified by various
database elements.  Thinking about this last night I realized that I should
always be able to use the current node as the context node and check if the
next element in document A exists in document B or not and if not, call some
template to generate it.  I'll hopefully be able to have a go at generating
the code this afternoon, but I somehow suspect I'll be posting about this
again...

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