PSoC6 project provides component-level APIs in a different way than PSOC3/4/5，it uses the integrated PDL library rather than Component based APIs, so the component datasheet is also different with before. These component name based .c/.h files are used to make an interface between the user and the PDL library, mainly to rename the function name to facilitate user to call PDL library. If you check I2CM.h, you can find full APIs provided here.
Thank you. Ok, it is just not mentioned in the datasheet at all as to what to do with I2CM functions. It would help if the document explained, as the functions found here ultimately all use the PDL function calls. So is this a legacy file which is there for backwards compatibility and therefore not recommended for new firmware etc, or something else. Just curious.