PAC 242 to PAC251 - APIs and Userexits


Does anyone know an easy way to migrate PAC version 242 to the last PAC version when you use plenty of USEREXITs and APIs?

May I consider RELEASE NOTES the only place where I could find the information whether there was any changes on APIs ans USERexits?

Is there a function or a specific documentation about the changes in these routines?