MARC import 020 match point
During MARC import, other 02X fields (022, 024, 028) only match on $a, but 020s match on any subfield, including $z, which is supposed to invalidate the following ISBN. Is it possible to modify the match points for 020s so that they only match on $a?
On a related note, just out of curiosity: in the MARC import settings, why are most match points referred to by field number (022, 1XX, etc.), but ISBN and UPC are referred to by name? (And wouldn't UPC already be covered by 024 $a, since the 024 match point doesn't look at indicators? Or am I misunderstanding?)