The reason WMVP was able to change their pattern and fill the null toward KOMO is that they changed the skywave model. XEOY is in the Region II database as a Class A and has to continue to be protected as such, even if they vacated the frequency. The Agreement Between Mexico and the United States requires that the old skywave model be used, so the WMVP null toward XEOY and Mexico remains just as deep as with the old three tower in line pattern.