As it stands, approximately 20 GB of data has been inscribed on-chain, raising concerns among certain users and developers about the efficiency and permanence of these inscriptions. Despite these concerns, the permissionless nature of Bitcoin allows users to freely add various types of data as long as they can cover the transaction fees. This freedom, however, brings to light the potential for more efficient methods of data inscription that avoid issues such as broken links and lost data.

Research into the matter suggests that Bitcoin transactions inherently possess the necessary components to decode data, such as images or text, without the need to store extra information in the witness data. This approach not only simplifies the process but also ensures that the integrity of the data remains intact without overburdening the blockchain with additional storage requirements.

A notable solution to this problem involves utilizing nLockTime, a feature within Bitcoin transactions that has been explored in depth in a stackexchange Q&A. By leveraging nLockTime, it is possible to generate off-chain images or other forms of data without directly storing them on the blockchain. This method was demonstrated through a proof of concept that could produce different images, such as a pixelated cube, based solely on the nLockTime value of a transaction. This approach not only addresses privacy and censorship concerns but also ensures that these transactions remain indistinguishable from standard Bitcoin transactions. Moreover, this technique implies that any Bitcoin transaction has the potential to be decoded into an image or another form of data, offering a vast array of possibilities for creative expression and data encoding on the blockchain.

It is important to note that while the CAT-21 project serves as an example of what could be achieved through this methodology, it does not imply an endorsement of the project itself. The inspiration for CAT-21, which involved minting cats for free as indicated in a referenced tweet, showcases the broader applicability and interest in finding innovative ways to utilize Bitcoin's existing capabilities for data inscription and retrieval without necessitating additional changes to the blockchain's structure.