What if we already have OP_CAT?

[amaclin1]

https://mempool.space/ru/tx/51bae58fa9d413b86d74da60d5366987dcdeb0586d39b93b2ca22f9e40dc83de

[DaCryptoRaccoon]

Code:

bc1p8nlum90ta46vtnlej0mefkku8pczym0zd6ppud8hqj2c9r9qx9zqv0v4jz
‎0.00020000 BTC
Witness	
5768617420
696620
776520
616c726561647920
6861766520
4f505f4341543f
7e7e7e7e7e1f5768617420696620776520616c72656164792068617665204f505f4341543f87
c079be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798
P2TR tapscript	
OP_CAT
OP_CAT
OP_CAT
OP_CAT
OP_CAT
OP_PUSHBYTES_31 5768617420696620776520616c72656164792068617665204f505f4341543f
OP_EQUAL
nSequence	0x00
Previous output script	OP_PUSHNUM_1
OP_PUSHBYTES_32 3cffcd95ebed74c5cff993f794dadc3870226de26e821e34f70495828ca03144
Previous output type	V1_P2TR

[BlackHatCoiner]

So here's what's going on in here.

In tapscript, the hex value 0x7e (or 126 in decimal) is a valid opcode (OP_SUCCESS) and you can verify that by looking at the validation of tapscripts. However, when Satoshi designed the first client, he assigned that value (126, 0x7e) as the OP_CAT value, which is disabled (verify that by looking in here). Therefore it's either a mistake of mempool.space which instead of OP_SUCCESS, displays OP_CAT, or maybe deliberate choice to support the potential upcoming softfork.

You cannot concatenate two strings in Bitcoin, as we speak.

[amaclin1]

So here's what's going on in here.

so, we see script ( "What " + "if " + "we " + "already " + "have " + "OP_CAT?" ) equals ( "What if we already have OP_CAT?" )
but it executes as trivial "return true"?  

If you read "buffalo" on an elephant's cage, don't believe your eyes.
(c) Kozma Prutkov, 1854

[pooya87]

So here's what's going on in here.

so, we see script ( "What " + "if " + "we " + "already " + "have " + "OP_CAT?" ) equals ( "What if we already have OP_CAT?" )
but it executes as trivial "return true"? 

If you read "buffalo" on an elephant's cage, don't believe your eyes.
(c) Kozma Prutkov, 1854

There is no OP_CAT anymore. The script inside a Taproot script is interpreted differently and when it encounters 0x7e, it is interpreted as OP_SUCCESS.

What are you trying to do here?
You know OP_SUCCESS is nonstandard and such transactions won't propagate, right? It would be difficult for you to create that branch, convince someone to send coins to, then spend it using OP_SUCCESS

[amaclin1]

What are you trying to do here?

I am just asking questions.
These are not my transactions (funding&spending), but I am interested in bitcoin innovations

You know OP_SUCCESS is nonstandard and such transactions won't propagate, right?

Today I know about it. A week ago I didn't

[BlackHatCoiner]

The transaction was created by @rot13maxi, a supporter of OP_CAT: https://x.com/rot13maxi/status/1822342752505413814.

There is no OP_CAT anymore.

I read that OP_CAT was disabled in 2010. Is there any recorded transaction that used it before that?

You know OP_SUCCESS is nonstandard and such transactions won't propagate, right?

Here's a fun way to spot a non-standard transaction: If the transaction fee is a round number, it was probably constructed by hand! 

[amaclin1]

I read that OP_CAT was disabled in 2010. Is there any recorded transaction that used it before that?

not in bitcoin blockchain (executed part of scripts)