This is a purely UK invention that is not compliant with JAR-FCL 1. The theory is that some elements of the 25 hours of CPL training in a MEP aeroplane duplicate some elements of the 6 hour MEP class rating course. By some twisted logic it was therefore decided that 3 hours of the CPL training could be credited to the MEP (or vice versa) and the combined course thus ended up at 28 hours instead of 31. It will be swept away by the adoption of the EASA Implementing Rules next year.