An article to understand the Ordinals family on Bitcoin

**What is the Ordinals Agreement? **

**The Ordinals protocol can be simply understood as a system for numbering Satoshi (SATS). **By giving each Satoshi a serial number, and then attaching additional data (text, pictures, codes, etc.), which is often referred to as "metadata" in NFT, each Satoshi becomes a unique NFT. The process is called "imprinting" or "burning".

"Satoshi" is a unit named after Satoshi, the inventor of Bitcoin, and represents the smallest denomination of Bitcoin. One Bitcoin can be divided into 100 million Satoshi. Individual satoshis are originally fungible, but once they are numbered with Ordinals, they become non-fungible tokens (NFT).

According to the Ordinals protocol, satoshis are numbered according to the order in which they were mined. Therefore, the number can also be used to define the scarcity of each slave. In an article about the Ordinals theory, the founder Casey Rodarmot proposed a table of the rarity of Bitcoin NFT. The specific classification is as follows:

• Common (Common): Any satoshi except the first satoshi of the block (total supply is about 2100 trillion)
• Uncommon: the first satoshi of each block (total supply is 6929999)
• **Rare: **First satoshi per difficulty adjustment period (total supply 3437)
• **Epic: **First satoshi after each halving (total supply is 32)
• **Legendary: **First satoshi per cycle (total supply of 5)
• **Mythic: **The first satoshi of the genesis block (total supply is 1)

The proposal of the Ordinals protocol makes Bitcoin no longer limited to value storage and payment functions, and helps to break the monopoly of the Bitcoin ecosystem. Therefore, even though it has been less than half a year since it was proposed, the Ordinals "family" has developed rapidly. At present, multiple branch protocols have been derived around Ordinals. The project has more new ways to play.

Fungible Token****BRC-20

**BRC-20 is a homogeneous token issuance standard on the Bitcoin network, which stipulates a series of functions such as the name, issuance, and transfer of tokens. **

BRC-20 is based on the Ordinals protocol. When the data written into SAT is minted in a unified JSON format, homogeneous tokens can be generated. Therefore, the inscriptions of tokens marked on BRC-20 are all text in a unified JSON format Data (Text).

Take the ORDI token in the following figure as an example. The deploy, mint, and transfer in the op field represent token deployment, casting, and transfer operations, respectively. Tick represents the name of the token to be executed. The maximum amount of minting of a single currency, amt is the number of tokens performed in a minting or transfer operation.

ORC-20

ORC-20 is an optimized version of BRC-20.

ORC-20 aims to enhance the functions of the BRC-20 protocol. ORC2-20 is backward compatible with BRC-20, expands the functions of BRC-20 and cancels some restrictions, and can better adapt to the needs of the project.

For example, ORC-20 has canceled the 4-character name restriction of BRC-20 tokens; the upgrade function of tokens has been added, so that project parties can do more empowerment based on tokens (reduce supply, increase scarcity, etc.); Added some advanced features (casting whitelist, royalties, etc.), and reduced the risk of BRC-20 double spending through UTXO, etc.

**In short, the ORC-20 protocol is more flexible than BRC-20, and has more application scenarios, and the user experience is closer to the ERC-20 tokens on Ethereum. **

BRC-21 and BRC-42

BRC-21 and BRC-42 are cross-chain versions of BRC-20.

Both BRC-21 and BRC-42 are cross-chain solutions for BRC-20 tokens proposed by Alexei Zamyatin, the founder of the cross-chain project Interlay, aiming to connect BRC-20 tokens in a fully decentralized manner** To external smart contract chains such as Ethereum, Solana, Polkadot, Interlay, etc., thereby unlocking the DeFi usage scenarios of BRC-20 tokens. **

**BRC-21 and BRC-42 have the same function but in opposite directions. **In simple terms, BRC-21 is to deploy assets from external blockchains to the Bitcoin network, while BRC-42 is to deploy BRC-20 tokens to other chains.

The deployment format of the BRC-21 and BRC-42 is largely the same as the BRC-20, with some specific functional differences.

Taking BRC-21 as an example, BRC-21 added src and id fields on the basis of BRC-20, where src is used to specify the "source chain" of the asset (such as Ethereum), and id is used to specify the target on the chain Token, that is, the contract address of the token; in addition, BRC-21 changes the field max of the total amount of issuance to optional, because the total amount is generally stipulated on the "source chain", and the restriction on single casting is cancelled. The amount of lim field, this is because following the strict casting and redemption rules, there is no need to make restrictions here.

Non-Fungible Token****BRC-721

BRC-721 is an experimental standard for issuing non-homogeneous tokens (NFT) on the Bitcoin network, **Compared with native Ordinals NFT, it has richer functions and higher flexibility. **

The BRC-721 standard defines a series of operations, such as deployment, minting, transferring NFT, updating metadata, etc. Each Token is given a unique identifier to ensure the uniqueness of each NFT so that it cannot be paired with other NFTs One exchange.

**Using the BRC-721 standard, users can easily create, mint, transfer and update unique digital assets for a wide range of application scenarios, including digital art, collectibles and virtual goods, etc. **

BRC-721 can support storing pictures in off-chain services such as IPFS, which can not only save the space of the Bitcoin network, but also provide flexible attribute information for each NFT. BRC-721 can support fields such as Trait, and can define NFT attributes and rarity information.

In addition, the Token URI and Metadata specifications adopted by BRC-721 are consistent with ERC-721, and have higher compatibility with the existing NFT ecosystem.

Therefore, compared with the original Ordinals NFT, using the BRC-721 protocol can achieve more complex functions, introducing external resources into Ordinals, which has stronger scalability, richer application scenarios, and is more friendly to developers.

Generative BRC-721

**Generative BRC-721 is an NFT protocol designed to reduce the cost of issuing and minting NFTs for project parties and users. **

Since the Bitcoin network itself does not support smart contracts and the upper limit of the block capacity, it is very costly for the project and users to issue the original Ordinals NFT directly by uploading pictures, and storing data in off-chain servers is against decentralization The original intention of decentralization, and Generative BRC-721 proposes a completely decentralized way to solve this problem.

Take for example OrdiBots, the first NFT series released by Generative BRC-721.

Although each NFT is a normal picture from the front end, the project party did not upload each picture to the Bitcoin network to complete the issue, but now the characteristics of this series of NFT images Split, such as background color, head shape, facial expression, etc., and then number these features, for example, the purple background is #1, the gray background is #2, and finally these features "parts" and "index instructions "Uploaded to the Bitcoin network to complete the issuance.

For users, what is minted is also the "Index Manual" corresponding to the NFT (below), not the complete picture. According to this "Manual", all the features of the NFT can be found, and then a normal picture (above) can be formed picture).

Through this method of "only uploading features and then combining", Generative BRC-721 can greatly reduce the occupation of NFT on the Bitcoin network during the entire issuance and casting process, so it can also reduce the cost of project parties and users when using it.

Derivative****SRC-20

SRC-20 is a token issuance standard based on the STAMPS protocol.

In addition to issuing homogeneous SRC-20 tokens, the STAMPS protocol can also issue non-homogeneous tokens. This kind of NFT is called Bitcoin Stamp.

BRC-20 is based on the Ordinals protocol, and the principle is to write arbitrary files in the witness data of Bitcoin transactions. However, the process nodes are capable of pruning or eliminating witness data, and not all nodes are required to retain or propagate witness data. And for the STAMPS protocol, since the information is stored in UTXOs, every full node must store them, so it is more "blockchain-native" than Ordinals.

Simply put, the biggest difference between the two is that **ORC-20 stores data in witness data, while SRC-20 stores data directly in transaction data. **Purely technically speaking, the SRC-20 would be more secure.

However, the disadvantage of SRC-20 is also obvious. It can store data in a smaller space. At present, it can only accept images with a maximum of 24x24 pixels or 8 color depths.

In terms of code format, the text used to deploy, mint and transfer SRC-20 tokens is also in JSON format, which is almost the same as BRC-20.

Fork****LTC-20 and DRC-20

LTC-20 and DRC-20 are "forked versions" of BRC-20 on the Litecoin network and Dogecoin network initiated by the community.

The same as the original BRC-20 concept, LTC-20 and DRC-20 are also based on the Ordinals protocol to provide users with the function of "engraving" text, pictures, codes and other data into their respective smallest unit tokens.

**Compared with BRC-20, the biggest advantage of LTC-20 and DRC-20 is that it can handle a large number of transaction needs at a lower cost and faster transaction speed, and there is no difference in essence from BRC-20 . **

In addition, another advantage of LTC-20 lies in the narrative of halving. Litecoin is expected to be halved in August. With the blessing of BRC-20’s wealth creation effect and halving narrative, LTC-20 may have a better chance of attracting investors in the market. attention and funding.