Crossed Recessed Countersunk Head Tapping

Crossed Recessed Countersunk Head Tapping - Applicable to screw types as indicated by code symbols.
Type AB thread forming.
Type A thread forming, except for short lengths.
Types B and BP thread forming; and Types BF and BT thread cutting
Type C thread forming; and Types D, F, G, and T thread cutting.
Head dimensions not shown are the same as those of slotted heads.
Where specifying nominal size in decimals, zeros preceding decimal and in the fourth decimal place shall be omitted.