Can't tell the difference between OP_CAT and OP_NET? What's the relationship with Fractal?

Author: OP_NET Chinese Community, Source: Author’s Twitter @opnetbtc_cn

Long story short:

• OP_CAT is an opcode in Bitcoin script, used to process data in Bitcoin transactions;

• OP_NET is a meta-protocol built on Bitcoin, used to issue, trade, and manage assets that meet protocol standards;

• Fractal is a side chain independent of Bitcoin, used to expand Bitcoin’s functionality, increase transaction speed, and enable more complex applications.

About the example

The classification meaning of the example diagram is greater than the architectural meaning, and it does not represent the real hierarchy. The actual situation is a complex relationship of "you in me, I in you".

For example, OP_CAT, as part of the Bitcoin script function, can be classified as the basic layer; Fractal can have OP_NET while adopting OP_CAT; in the protocol layer, more advanced functions can also be achieved by calling OP_CAT and other script opcodes...

OP_CAT

OP_CAT is part of the earliest Bitcoin script opcodes. In order to avoid possible vulnerabilities (potential denial of service DoS attacks due to unlimited memory usage), Satoshi Nakamoto disabled multiple opcodes, including OP_CAT. BIP-420 is a proposal specifically proposed to reintroduce OP_CAT, hoping to restore OP_CAT in a new way, and BIP-420 is just the number of the proposal.

OP_NET

As a protocol standard for issuing, trading, and managing assets, is it the same type of thing as an opcode? It should be compared to Ordinals/Runes, etc. It uses a Wasm-compiled indexer to achieve multi-language compatibility and execute smart contract operations in the index. The account model is adopted, and all transactions use BTC as gas. If this is still difficult to understand, just remember: there are smart contracts; using BTC as gas is enough.

Fractal

As a sidechain independent of Bitcoin, Fractal's advantages are: lower fees, larger capacity, and faster speed. While trying to keep consistent with the main network (without modifying Bitcoin Core and POW), it may try to expand smart contracts (depending on its design). As for whether it can eventually grow and develop, it depends on the consensus result. However, it does not prevent OP_NET & OP_CAT from conducting experiments on this.

Summary

In addition to the similar names, the greatest common divisor of OP_CAT and OP_NET is the extension of smart contracts, but the implementation methods are different. If OP_CAT hopes that BIPS (Bitcoin Improvement Proposal) will be passed to modify Bitcoin itself to achieve the purpose of expanding contracts on the main network.

Then OP_NET provides an optimal solution in a realistic situation, bypassing it. At least for now, no solution beyond this route has been found.

Leave a question: Do you think the reactivation of OP_CAT can be considered a modification to Bitcoin core? If not all nodes in the network understand and accept new transactions using OP_CAT, if some nodes are not updated, can it be a soft fork?

First state the position and definition of modification: I personally believe that activation is from existence to non-existence and then to existence, which actually makes a difference. Addition, deletion, existence, and non-existence are all modifications.