actuallly i sent the aamc an email about that and i got this response
Race/ethnicity is self description; that is you decide what you consider yourself. We do not differentiate between mainland and Commonwealth Puerto Ricans.
Hope this is helpful and good luck.
Lily May Johnson
Manager
AAMC
Division of Diversity Policy and Programs
2450 N Street, N.W.
Washington, D.C. 20037 [email protected]
202-828-0573 (phone)
202-862-6282 (fax)