Their proposed format incorporates the binary encoding from BIP174 PSBT, aiming to make it compatible with PSBTv1 and PSBTv2 by allowing a coordinating device to add inputs or an unsigned transaction without additional modifications. This initiative includes introducing two new global map entries: PSBT_GLOBAL_DESCRIPTOR and PSBT_GLOBAL_KEY_NAME, with specific keys and values to hold the descriptor information.

The preliminary design of SeedHammer's descriptor format adheres to the standards set forth in BIPs 380-386 and BIP 389, utilizing Miniscript while discouraging inline keys and requiring substitutions of pk(NAME) expressions with indexed key references. It also integrates extra metadata like labels and birthdate blocks via PSBT map entries. The debate within the community partly revolves around the choice of encoding method—CBOR versus PSBT—with Blockchain Commons suggesting CBOR due to its status as an established standard. However, SeedHammer maintains that PSBT's simplicity and current support in wallet software make it a more practical choice despite CBOR's complexity.

Another aspect under discussion is whether to create a unique header and magic number for the new format or to extend the existing PSBT format. As part of the development process, SeedHammer seeks feedback on their proposal to refine it before submitting it for formal consideration through the BIP process. For those interested in reviewing the details of this proposal, examples and further information are accessible via the links provided for the proposal, its implementation, and a playground for experimentation.