Standard Unstructured Annex

The discussion revolves around the integration of taproot annex support into Libre Relay, a project detailed through a specific commit on GitHub (see commit). This development is influenced by an existing pull request by Joost Jager on the Bitcoin repository (view pull request), setting forth criteria for transactions containing taproot annexes to be considered standard. The primary conditions outlined for such transactions include the initiation of all non-empty annexes with byte 0x00. This specification is crucial for differentiating these annexes from those that may be deemed consensus-relevant in the future, thereby avoiding potential conflicts with subsequent soft-forks which could assign new meanings to the annexes.

Moreover, there is a stipulation that all inputs within a transaction must have an annex, positioning the use of the annex as an opt-in feature. This requirement aims to mitigate the risk of transaction pinning attacks within multi-party protocols. However, it's acknowledged that this criterion might be loosened in the future to accommodate the spends of keyless outputs or the implementation of Replace-by-Fee (RBF) for witness-only replacements. An example transaction provided meets the above requirements, demonstrating how these guidelines are applied in practice.

This initiative is part of ongoing discussions and efforts within the Bitcoin Development Mailing List, a platform for contributors like the sender of this message, to discuss innovations and changes to Bitcoin's protocol and related projects. The sender also provides a link to their personal website for further contact and information (Peter Todd's website) and mentions their subscription to the mailing list as the basis for receiving this update.