L - Spall over  2  ft.  (0.6  m)  long:  (1)  spall  is broken into no more than three pieces defined by low- or medium-severity cracks; little or no FOD potential exists; or (2) joint is lightly frayed; little or no FOD potential. Spall less than 2 ft. long is broken into pieces or fragmented with little FOD or tire damage potential exists.

Lightly frayed means the upper edge of the joint is broken away leaving a spall no wider than 1 in. (25 mm) and no deeper than ½  in. (13 mm). The material is missing and the joint creates little or no FOD potential.

M - Spall over 2 ft. (0.6 m) long: (1) spall is broken into more than three pieces defined by light or medium cracks; (2) spall is broken into no more than three pieces with one or more of the cracks being severe with some FOD potential existing; or (3) joint is moderately frayed with some FOD potential. Spall less than 2 ft. long: spall is broken into pieces or fragmented with some of the pieces loose or absent, causing considerable FOD or tire damage potential.

Moderately frayed means the upper edge of the joint is broken away leaving a spall wider than 1 in. (25 mm) or deeper than ½  in. (13 mm). The material is mostly missing with some FOD potential.

H - Spall over 2 ft. (0.6 m) long: (1) spall is broken into more than three pieces defined by one or more high-severity cracks with high FOD potential and high possibility of the pieces becoming dislodged, or (2) joint is severely frayed with high FOD potential.