OP_PUSHDATA4 ​

The OP_PUSHDATA4 opcode will read the 4 bytes that follow it and interpret them as an integer. It will then push the next number of bytes this integer specifies onto the stack. Because it reads 4 bytes and inteprets them as a number, this opcode can push any number of bytes from 0 to 4,294,967,295. Since the largest data push allowed by consensus rules is 520 bytes for which it is more efficient (and required by standardness rules) to use OP_PUSHDATA2, this opcode is never used in practice (see minimal push operations).

OP_PUSHDATA4 is part of a group of 3 opcodes that push a custom, user-specified number of bytes onto the stack (its sibling opcodes are OP_PUSHDATA1 and OP_PUSHDATA2).