ok, i think i might have figured it out. can someone tell me if this way of ascertaining the difference is valid?

with calipers, i measured the cross-section of the spindle where the taper begins (frame side).

miche: .53"
shimano: .55"
phil: .53"

not much difference, but there was a difference. by these measurements, the phil is more similar to the miche--therefore, it's ISO.

but is this a valid way to ascertain the difference?