It is Northfield Ambulance, dispatched by Allina EMS. there are a couple typos with some of the smaller ambulance services that migrated early to ARMER that are dispatched by Allina or North EMS...
in some of the north memorial radios i have seen programmed with the Northfield EMS talkgroup, its alpha tag is NFIELD, but EMSAL_NFD would also be a very appropriate alpha tag (EMS, Allina, Northfield)...