In musical rights management, the CAE/IPI number is used to identify rights holders. The CAE [CAE is the acronym for Composer, Author, Editor (a/k/a Publisher)] Number is a number assigned to every writer or publisher in the world who is affiliated with a performing or mechanical rights society. This number is assigned when you become a writer or publisher member.
Your PRO (ASCAP, BMI, SESAC, or SOCAN) membership number is NOT the same as your CAE/IPI number. This number is critical for you to get paid, so please make sure this number is accurate. Do not simply paste in a random number just to get through the process.