For-Each-Group
Groups the items in a list by a specified element. This statement requires a Grouping statement to specify which element to group-by.
See Converting a List Into a Grouped List for an example of using the For-Each-Group statement.
XSLT Equivalent
<ns0:for-each-group xmlns:ns0="http://www.w3.org/1999/XSL/Transform" select=""/>