Main Engine Cut OffThe Mayhem of Docking Adapter Standards
Pete Harding for NASASpaceFlight:
As a result, the plan became to build the IDAs with the SIMAC system, in order to convert the APAS-equipped PMAs to the IDSS-compatible SIMAC-based NDS, which will be used on future commercial crew and exploration vehicles.
This article is a great rundown of how we got to this point, with far too many acronyms and docking systems. Relevant xkcd.