We often have the need to attach multiple signatures to a transaction. So we may need to partially sign a transaction and then send to someone else for adding a signature. This was difficult to be done because of different implementations. For these reasons a new standard has been created (proposed with BIP174) in order to make easy to apply multiple signatures to a transaction in a way that does not depend on wallet implementation.

The signature requires the possibility to access to UTXO by each participant. With this format, it is therefore possible to sign transactions offline or airgapped in an easy way. Infact it is now going to be supported by a lot of wallets, for example the well known coldcard wallet, which works airgapped.

Coldcard in particular, is a native pbst wallet. This means that it uses pbst as internal format and it is able to sign any transaction in pbst format, doesn’t matter which wallet generated such transaction. Finally it can generate another pbst file or a finalized transaction ready to be broadcasted.

Coldcard wallet supports pbst transaction format

Personally i’ve tested coldcard and the signature process is very smooth when done, for example, using electrum wallet software. Obviously the fact of maintaining it as argapped means some more step in doing the signature, but the bottom line is a great security during all the process, even if many signatures are involved.