Script – What is OP_CAT suggestion?

OP_CAT was the opcode. 0x7e In the script version of the original Bitcoin release. It was disabled along with several other instructions in 2010 when a bug in another instruction was discovered. Before being disabled, the resulting stack items were limited and that limit was further lowered.

OP_CAT pops the top two values ​​from the stack, concatenates the popped values ​​in stack order, and pushes the result on top of the stack. BIP 347 proposes that OP_CAT be added to Tapscript as follows: 0x7eRedefine OP_SUCCESS126. This will allow OP_CAT to be used in P2TR version 0 leafscripts.