I know, but can you tell me the specific meaning of tapscript (Many previously disabled opcodes are redefined to be OP_SUCCESS opcodes that unconditionally render the entire script valid to simplify soft fork upgrades.)? I don’t understand what OP_SUCCESS specifically redefines? How is it used?
In tapscript when the interpreter encounters one of the OP_SUCCESSx opcodes, it instantly succeeds. In the future this might change, and some opcodes might enforce restrictions - soft fork. But the future is not here yet, so nobody knows what and how exactly would happen. So there was OP_CAT at the very beginning, then it was disabled, and now inside tapscript there's OP_SUCCESS126 instead, which might change (in future tapscript version) to something else (instead of instant success).
Here is the list of the codes redefined as OP_SUCCESSx, the red ones were disabled in usual script:
OP_RESERVED = 0x50,
OP_VER = 0x62,
OP_CAT = 0x7e,
OP_SUBSTR = 0x7f,
OP_LEFT = 0x80,
OP_RIGHT = 0x81,
OP_SIZE = 0x82,
OP_INVERT = 0x83,
OP_AND = 0x84,
OP_OR = 0x85,
OP_XOR = 0x86,
OP_RESERVED1 = 0x89,
OP_RESERVED2 = 0x8a,
OP_2MUL = 0x8d,
OP_2DIV = 0x8e,
OP_MUL = 0x95,
OP_DIV = 0x96,
OP_MOD = 0x97,
OP_LSHIFT = 0x98,
OP_RSHIFT = 0x99,
and everything between
OP_CHECKSIGADD = 0xba,
and
OP_INVALIDOPCODE = 0xff,