LIT-18 is not published or shared out side of FieldComm Group. This document is required for testing in our labs, it describes the device and the HART commands implemented.
All of the implemented commands must be listed in the LIT-18.
Device-specific commands or commands which are for test/developer purposes only are still required to be listed in LIT-18 and can be listed as non-public commands.
Here is the table of contents from the template provided in the HART Registration Kit: