OP_MOD ​
INFO
Opcode number: 151
Byte representation: 0x97
Short description: Fail the script unconditionally, does not even need to be executed.
OP_MOD is a disabled opcode in the bitcoin scripting system.
Historical Context ​
OP_MOD was designed to perform a modulus operation, which would find the remainder after dividing the second-to-top stack item by the top stack item.
Due to concerns about potential vulnerabilities and the desire to simplify the scripting language, OP_MOD (along with several other opcodes) was disabled early in bitcoin's development.
Operation ​
Because OP_MOD is disabled, any script that contains it will render the transaction invalid regardless of context.