#263 dst_fid called from($src_fid.keysrc_fid.key=) for must go as second after src; ancestor-or-self::src_fid/@key = ; count var
#128 src comes first upper
last preceding-sibling is correct for row-object count prec sib last
dst comes first next
#315 following-sibling stop
#89AAA preceding-sibling for count(preceding-sibling::*)= , count(following-sibling::*)=
#347 when test="$src_fid.key = @key"