I think the -48 is the contiguous 48 states.. I could be wrong but from a defense standpoint if they were warding an attack..then the prior code was associated with a protection algorithm in my best guess.
the -48 then restricts it to CONUS.
The follow on was to change the routing of POTUS and the number P_193 was a predetermined route/method.
I think the -48 is the contiguous 48 states.
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One of the anons suggested 48 hours...