We are excited to share the current progress on our research into the aggregation of signatures based on curve secp256k1: There is now an early draft Bitcoin Improvement Proposal (BIP) for non-interactive half-aggregation of BIP 340 Schnorr signatures. This proposal has a variety of potential applications in the Bitcoin ecosystem. Moreover, to the best of our knowledge, this would be the first BIP with a formal specification, which is a mathematically precise description of the scheme. The formal specification can be used to prevent multiple classes of security issues and potentially help future formal software verification efforts.