OP_LEFT

INFO

Opcode number: 128
Byte representation: 0x80
Short description: Fail the script unconditionally, does not even need to be executed.

OP_LEFT is a disabled opcode in the Bitcoin scripting system.

Historical Context

Originally, the OP_LEFT opcode was intended to keep only the leftmost N bytes of a string. The operation would pop two items from the stack: the original string and a byte count. It would then push back onto the stack the leftmost bytes of the string, as specified by the byte count.

Due to concerns about potential vulnerabilities and the desire to simplify the scripting language, OP_LEFT (along with several other string manipulation opcodes) was disabled early in bitcoin's development.

Operation

Because OP_LEFT is disabled, any script that contains it will render the transaction invalid regardless of context.