I guess upgrade of Multi-Signatures is possible by accepting a new Multi-Signatures registration signed by the former keys.
implementation details are needed to ser/der the signatures and clarification on use of ECDSA and/or Schnorr and why
A special section for Schnorr MuSig to clarify why Multi-Signatures registration is NOT needed (even not recommended imo) for MuSig. And the implementation of MuSig is delegated on the client side only.
Also missing the specification on transaction v1 vs v2:
link to AIP18: https://github.com/ArkEcosystem/AIPs/blob/master/AIPS/aip-18.md
a few discussion about the current status:
Also missing the specification on transaction v1 vs v2: