so-called Separate Rations, the money enlisted folks in all service receive if they have permission to not eat in the mess hall. If you receive it,and eat in the mess hall anyway, you have to pay for your meals. Essentially it was designed for married enlisted guys but it generally applies in the Army, Navy and Marines to anyone authorized to not live in the Barracks, a minority. Don't know what the USAF does now but years ago they used to give it to almost everyone which always caused problems if you were in another service and not drawing BAS because the USAF Headcount guys refused to believe that you were not drawing it and were therefor entitled to eat for free...

TAD is the Navy and Marine same thing as USA / USAF TDY, Temporary Additional Duty / Temporary Duty. The money factor is that while on such orders people are paid a Per Diem rate that varies from locale to locale. Drawing that Per diem can include rations, quarters and incidentals $55 up to $300 or more a day, generally around a hundred and some change). If you are gone more that 180 days, it's not TAD /TDY ordinarily; thus the Marines and Navy with 7 month tours and the Army with 12-15 month tours do not draw per diem; that Air Force does 90 and 179 day tours in Iraq and Afghanistan and thus they get to draw per diem for the whole trip. A considerable windfall...

That, I think is changing. Dunno.