by Tsua00021

Dear Community,

PSBT standardizes how unsigned transactions are exchanged between participants, but it does not define a way for signers to independently verify that a transaction satisfies the economic rules expected by the protocol or workflow they agreed on.

In practice, multi-party PSBT workflows (e.g., marketplaces, batch payouts, shared expenses) often rely on imperative coordinator logic: calculating change amounts, ensuring output equilibrium, and managing fee bumping across multiple inputs. This logic is usually implemented in host software that signers must implicitly trust.

This post explores an experimental declarative schema for PSBT validation that I have been experimenting with: BTSL (Bitcoin Transaction Schema Language). It shifts from constructing transactions to specifying them.

BTSL introduces no new consensus rules and does not modify the PSBT format. It is purely a validation layer operating above BIP174/BIP370.

...read more at delvingbitcoin.org