> It seems like I should be able to do this in XSLT 1.0, but if all the great
> xslt minds on this list say no, then I'm sure I'm wrong.

You could do it via a recursive template but you'd have to keep
re-calculating your grouping key which is quite expensive
you can only get the benefit of using a key to speed things up if the
key value can be expressed as a single xpath which it can't in your
case.
So unless you _really_ need it to be a single pass without any extension
function (in which case ask again) I'd definitely do it in two passes,
first collecting together the grouping key then either in  asecond
transformation or via node-set,do the grouping.

David

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