Different areas of the fire usually determined by the predominant direction of fire spread and delineated from the fastest moving area (head) to the slowest moving area (base or tail). The most rapidly moving portion is designated the head of the fire, the adjoining portions of the perimeter at right angles to the head are known as the flanks, and the slowest moving portion is known as the rear or the base of the fire. 

The most rapidly spreading portions of a fire’s perimeter, usually progressing with the wind, up slope, or a combination of the two.

That portion of a fire edge opposite the head.

That portion of a fire backing directly away from and in relatively close proximity to the ignition area. The slowest spreading portion of a fire edge and generally opposite the head.

The use of fire to accomplish a specified objective.

The organizational element having responsibility within a functional area in the incident command structure such as operations, planning, logistics or finance.

In the 1978 version of NFDRS, the herbaceous stage when herbaceous fuel moisture is between 120% and 30%.

Primary facility of the Multi-agency Coordination System (MACS); houses staff and equipment necessary to perform the MACS function.

Measured from the surface upward, the height to which relatively vigorous mixing occurs due to convection.

Debris resulting from such natural events as wind, fire, or snow breakage; or such human activities as road construction, logging, pruning, thinning, or brush cutting. It includes logs, chunks, bark, branches, stumps, and broken understory trees or brush.