By all means reply but from an educational perspective point out that
your preference for for-each-group,  has no set-theoretic
interpretation,

It's iterating through representatives of the quotient set if you factor
by the relation implied by the group-by clause.

will not work for anybody restricted to XSLT 1.0

It's easy to rewrite any such use of for-each-group as xsl-for-each plus
a filter using a key (look up muenchian grouping for the details)

and does not port to XPATH or XQuery.

For xquery you can use the similar group-by clause so long as you
are using V3 http://www.w3.org/TR/xquery-30/#id-group-by

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