Once Protocol 19 is voted in, it will introduce two CAPs, [CAP-21](https://stellar.org/protocol/cap-21) and [CAP-40](https://stellar.org/protocol/cap-40), alongside a new StrKey (see [SEP-23](https://stellar.org/protocol/sep-23)) for signed payload signers. Documentation work includes the following: - [x] Changes to the Horizon API: the [transactions](https://developers.stellar.org/api/resources/transactions/) and [accounts](https://developers.stellar.org/api/resources/accounts/) objects have new, optional fields (see the [community SDK blast](https://github.com/StellarCN/py-stellar-base/issues/583) for a summary of changes) - [x] Signed payloads as an [alternate signature type](https://developers.stellar.org/docs/glossary/multisig/#alternate-signature-types) - [x] A discussion of the new preconditions in both transaction [attributes](https://developers.stellar.org/docs/glossary/transactions/#time-bounds) and transaction [validity](https://developers.stellar.org/docs/glossary/transactions/#validity-of-a-transaction) - [x] The new txMALFORMED error code as a [transaction result code](https://developers.stellar.org/docs/glossary/transactions/#result-codes) - [ ] Possibly, a new glossary entry on payment channels, or amendments to [Channels](https://developers.stellar.org/docs/glossary/channels/)
Once Protocol 19 is voted in, it will introduce two CAPs, CAP-21 and CAP-40, alongside a new StrKey (see SEP-23) for signed payload signers.
Documentation work includes the following: