if Hospital Wing 7 is based in oxford MS ....

If "Hospital Wing 7" is based at Hospital Wing Base 7 in Oxford MS -
then what is "Hospital Wing 7"?

"Hospital Wing 7" is actually the 'over the air spoken radio ID' for
the helo - as used in communicatiopns between the medevac aircraft
and the medevac dispatcher

its not the CAD ID because the CAD ID might be "HW7" or "HWseven" or anything

its not the FAA ID because the FAA ID would be N-something - its
called the N numner or maybe the aircraft registration number

adbs will have another unique ID - mixture of number and letters iirc

its not the fema resource type identifier - because that would be
'medevac type 2' or whatever

it might not be the air to ground ID to the local VFDs - they might
just call it "Helicopter guy"

it wont be the TRS ID because that might be ghq70001002000300040005 or whatever

its not the ID used on the ATC freqs - that might be Lifeguard
Hospital Wing 7 or Medevac Hospital Wing 7 - pretty sure that FAA ATC
has 2 specific identifiers (pro words / flight ID prefixes) for
medevac aircraft - one for emergency - one for non emergency flights
iirc - that might be the same ID that is entered into the FAA flight
plans and FAA flight tracking programs