14 CFR subchapter F part 89 subpart D and E describes the information desired for compliance accepted by FAA in a document of compliance.
Remote identification broadcast modules must be capable of broadcasting the following remote identification message elements:
(a) The identity of the unmanned aircraft, consisting of the serial number assigned to the remote identification broadcast module by the person responsible for the production of the remote identification broadcast module.
(b) An indication of the latitude and longitude of the unmanned aircraft.
(c) An indication of the geometric altitude of the unmanned aircraft.
(d) An indication of the velocity of the unmanned aircraft.
(e) An indication of the latitude and longitude of the take-off location of the unmanned aircraft.
(f) An indication of the geometric altitude of the take-off location of the unmanned aircraft.
(g) A time mark identifying the Coordinated Universal Time (UTC) time of applicability of a position source output.
Means of Compliance
A person designing or producing a Standard Remote ID drone or broadcast module for operation in US airspace must show that they have met the requirements of the remote ID rule by following an FAA-accepted means of compliance. A means of compliance describes the methods by which the person complies with the performance-based requirements for remote ID.
It's important to note that producers do not need to develop and submit their own means of compliance for FAA acceptance. They can use any means of compliance accepted by the FAA, including one developed by a third party.
How to Submit a Means of Compliance
A means of compliance describes how a manufacturer may comply with the performance requirements for a Standard Remote ID Drone or a remote ID broadcast module. Anyone may submit a means of compliance for FAA evaluation and possible acceptance. In particular, the FAA encourages consensus standards bodies to develop means of compliance and submit them for acceptance because these bodies generally incorporate openness, balance, due process, appeals process, and peer review.
However, FAA-accepted consensus standards are just one way, but not the only way, to show compliance with the performance requirements of this rule. The FAA emphasizes that although a means of compliance developed by a consensus standards body may be available, any individual or organization can submit its own means of compliance for consideration and potential acceptance.
LEOs might need 15 different readers and carry them around in the already cram packed patrol vehicle just in order to identify a drone.
DJI's implementation might be different than Autels. So basically, DJI could just submit their implementation and have it approved to make FAA happy. They might have to make a few changes to their implementation, but practically the hardware is already there.