I'm certainly not an expert, but it does say
"Contiguous US ADIZ" in addition to
"Mexico FIR MMFR"
Also this item from the FAA website specifically says there is no ADIZ between the US and Canada, but fails to mention the same for Mexico. It also mentions additional requirements for Defense VFR flight before penetrating the ADIZ.
"Air Defense Identification Zone (ADIZ)
All aircraft entering U.S. domestic airspace from points outside must provide for identification prior to entry or exit. ADIZs have been established to assist in early identification of aircraft in the vicinity of international U.S. airspace boundaries (AIM Section 6, 5-6-1).
Many aircraft inbound to the U.S. will cross an ADIZ. There is no ADIZ between the U.S. and Canada. According to FAR Part 99, if penetrating an ADIZ, all aircraft of U.S. or foreign registry must file, activate, and close a flight plan with the appropriate aeronautical facility. In addition to normal ADIZ position reports, and any other reports Air Traffic Control may require, a foreign civil aircraft must give a position report at least one hour before ADIZ penetration, if it is not more than two hours average cruising speed from the U.S.
For Defense VFR (DVFR) flights, the estimated time of ADIZ penetration must be filed with the appropriate aeronautical facility at least 15 minutes before penetration, except for flights in the Alaskan ADIZ, in which case, report prior to penetration. Additionally, VFR pilots must receive and transmit a discrete transponder code."
View attachment 60961
Also from this recent AOPA article about flying into Mexico:
A step-by-step guide to planning a trip south of the border that covers procedures, permits, fees, and regulations.
www.aopa.org
" • 12-inch registration marks are required for crossing the ADIZ into Mexico."