How to create entityid for custom instrament

I am creating a custom instrument for a frogguiro which is a combination of a quiro and woodblock . my question is, what the rules are for creating the entityid and nameid. i will model the definition after drum set.

There are no particular rules. The main criterion is uniqueness. But I would advise against creating your own instrument definitions manually, even though I know it’s frustrating having to repurpose existing percussion instruments by changing their names etc. in the application.