The counterpart to OP_1ADD, OP_1SUB subtracts 1 from the top item on the stack. This opcode finds its use in scripts that require decrementing values, such as in countdowns, decrementing loops, or in adjusting values downward by a single unit.
OP_Code Walkthrough
Decrements the top item of the stack by 1
Pop Top Item
Substract 1 from Item
Push Item