Find list of custom BAPI

Dear Experts,

I want to find out the list of custom BAPI in system. In thread http://scn.sap.com/thread/81493 Rich Heilman Sir has mentioned that

BAPI can be named as Z* as well as BAPI* and that he is not sure which is correct. If BAPI* naming convention is followed by customer

then how can I track down the difference between SAP provided BAPI starting as BAPI* and customer created BAPI starting with BAPI*.

Please share your valuable inputs.

- Bharath