NATO acronym for
Atomical,
Biological and
Chemical. An attack with any of these weapons would be classified as an ABC attack, and personel must prepare for ABC mode combat. The large difference between the A and the B+C is of course that the atomic warfare results in enormous explosions while the biological and chemical do not detonate (Not of any importance, anyway.) That's why the ABC standards are
filtering and
shielding standards. A war ship is usually ABC compliant, vehicles can be ABC compliant, gas masks and combat suits can be ABC compliant etc. But none of them are made to resist a direct atomical attack, only
radiation and
fallout.
The ABC system also includes drills of personel in case of an ABC attack. These drills can be on a per person basis such as getting on gas masks in a time frame, or unit wide such as sealing off a M.A.S.H. unit and preparing it for attack.
NOTE: The acronym NBC for Nuclear, Biological, Chemical, is also used. The ABC term is used more in training of troops, since it's easier to grasp and remember.