Understanding how ordinals work with the Bitcoin blockchain. What is exactly stored on the blockchain?

Question

Supposedly someone uploaded a Doom clone to the bitcoin blockchain:

https://ordinals.com/content/521f8eccffa4c41a3a7728dd012ea5a4a02feed81f41159231251ecf1e5c79dai0

But I'm a bit confused on exactly what is uploaded using "Ordinals". From a quick read of Ordinals, I'm assuming they are just using OP_RETURN and putting in a encoded string into a block or a transaction?

This encoded string uploaded is a "id" that links to a file on ordinals.com? So technically no real files are uploaded like this Doom clone is it? And if ordinals.com is offline, none of these files are accessible?

And how is this different from colored coins or counterparty from about a decade ago?

Vojtěch Strnad · Accepted Answer · 2023-02-02T21:51:48.627

6

Ordinals Inscriptions don't use OP_RETURN, they are embedded within the script of a taproot input. It's not just a link to a file on some website, the entire file is actually published to the blockchain.

The embedding is done using data pushes inside an unexecuted script branch like so:

OP_0
OP_IF
(embedded data comes here)
OP_ENDIF

You can view the script from your specific example here: https://scriptpath.info/tx/521f8eccffa4c41a3a7728dd012ea5a4a02feed81f41159231251ecf1e5c79da
It consists of 59 pushes of 520 bytes each and one push of 73 bytes.

edited Feb 02 '23 at 21:51

answered Feb 02 '23 at 16:26

Vojtěch Strnad

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So that Doom clone is exactly how big on the blockchain and how much did it cost? – Patoshi パトシ Feb 02 '23 at 16:59
520*59 + 73 = 30,753 bytes. The transaction adds another 445 bytes of overhead for a total of 31,198 bytes (but, because of the witness discount, only 7870 virtual bytes). The fee paid was 19,675 sats. – Vojtěch Strnad Feb 02 '23 at 17:45
Any reason why they split the data in 520-byte chunks? – DeLorean88 May 09 '23 at 15:12
That's the maximum push size. You can search BIP141 and BIP342 for "520" to learn more. – Vojtěch Strnad May 09 '23 at 15:23
@Vojtěch Strnad How were you able to pin that that's the script – mark Jan 16 '24 at 20:28
@mark You can use any blockchain explorer that decodes Taproot scripts. Alternatively, you can decode the script yourself from the input witness. (If you have another question, please create it as a new post.) – Vojtěch Strnad Jan 16 '24 at 20:56

RedGrittyBrick · Answer 2 · 2024-01-16T18:46:43.917

2

The MIME data type of that inscription is text/html;charset=utf-8. So maybe it is something like Doom in javascript

Ordinals inscriptions do embed the data in transaction data that occupies space in the Bitcoin blockchain.

Understanding how ordinals work with the Bitcoin blockchain. What is exactly stored on the blockchain?

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