AP242 recommended practices are mandatory in order to know how to use the Application Protocol. It is the reason why, in parallell of the ISO standardization project, recommended practices have been defined in order to make the standard useable and effective.
They are managed by the CAx Implementor Forum : http://www.cax-if.org/joint_testing_info.html#recpracs
STEP AP242 AIM Model in P21 format : PDM Usage Guide
STEP AP242 TC Business Object Model in XML format
The objective is to ensure the bi directional conversion between the 2 implementation formats of AP 242.
Draft recommended practices started in a pilot with limited scope.
To be completed in 2014, related with the setting up of the PDM-IF.