The most current work from this project is reflected in the ASTM Remote ID Standard.
The scope of the standard includes both Broadcast and Network Remote ID as illustrated below. For broadcast, the scope comprehends exactly how the UAS must transmit each packet (the encoding is included in the c library on github) so that a compatible receiver app may be developed. For Network Remote ID, the focus of the standard is on interoperability between Network Remote ID USS participants. How (at the precise protocol level) each USS requires each UAS or client app to interface to it is outside of the standard scope.
The ASTM standard is developed in a way that it is expected that a regulator would create a “Policy Overlay” such as a “Means of Compliance” (MOC) or similar application document to adapt the standard to the specifics of the regulation. For example, the standard calls out several fields as “optional”. Some of those fields may actually be required per local regulation and the MOC could specify such standard “overrides”.