Question about being reactivated to active duty.

This is a question for all of the military dopers out there. Or anybody else who knows I guess. I’m not too picky. Does anybody know the process by which they select the folks who are on IRR back into active duty?

In broad terms, those military occupational specialties (Army) that are considered to be critical and recall based on the needs of the service. Retention specialists will look at longer term trends with respect to projected troop strength levels several years out. Linguists, military police and aviation assets would be examples of fields in which reservists might expect reactivation.