Jeni, Ken, Steve,

it's great when your questions are being answered by the pros :-)

Jeni's solution won in terms of speed and plugability (and in showing me that I
was 'almost' there, which was reassuring for my self-esteem :-))

So, thank you all - I have a working stylesheet now!

</Steven>

ps: question aside: does anyone has an idea on the efficiency of this
multi-level grouping thing? Both in terms of memory usage building up these
three massive keys, and for-eaching across all of them. There's a good chance
this transformation will be called (inside a Cocoon pipeline) quite often, and
while there's cacheing inside Cocoon, a performant stylesheet is a good starter.


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