Runestone

A Runestone is a set of encoded directives stored within the OP_RETURN field of a Bitcoin transaction. It serves as a blueprint for specifying the desired actions to be performed with Runes during that transaction.

For instance, a Runestone can contain instructions such as "Mint this particular Rune," "Etch a brand-new Rune," or "Transfer these specific Runes."

Without a Runestone, the default behavior is that all Runes present in the input UTXOs will be automatically transferred to the first non-OP_RETURN output of the transaction.

To deviate from this default and exercise more control, users can incorporate a Runestone and include an Edict, which provides explicit instructions on which Runes should be routed to which outputs.

Bitcoin currently imposes a limit of 80 bytes for data stored in the OP_RETURN field. While typical Runestones comfortably fit within this constraint, more complex transactions involving the arbitrary distribution of multiple Runes across numerous outputs (such as airdrops) may necessitate a larger Runestone.

Should Runes attain widespread popularity, the discussion around increasing Bitcoin's 80-byte OP_RETURN size limit could gain traction, as it would allow for more intricate Runestone instructions to be accommodated.

It's worth noting that most users are unlikely to interact directly with Runestones. Front-end providers are expected to abstract and streamline this process, offering a more user-friendly experience.