BTFSC (Bit Test and Skip if Clear) and BTFSS (Bit Test and Skip if Set) are used to test the bit and skip the next instruction, or not, according to the state of the bit tested. DECFSZ and INCFSZ embody a commonly used test – decrement or increment a register and jump depending on the effect of the result on the zero flag (Z is set if result 0). Decrement is probably used more often (see BIN4 delay routine), but increment also works because when a register is incremented from the maximum value (FFh) it goes to zero (00h).