10. The aim of the United Kingdom Radiotelephony Manual (CAP 413) is to provide pilots, Air Traffic Services personnel and other ground personnel, both civil and military, with a compendium of clear, concise, standardised phraseology and associated guidance, for radiotelephony (RTF) communication in United Kingdom airspace
14. All users of RTF in the United Kingdom are expected to comply with the phraseology described in this manual. However, the phraseology examples contained herein are not intended to be exhaustive, and when circumstances differ, pilots, ATS personnel and other ground personnel will be expected to use plain language, which should be as clear and concise as possible.
The Commercial COM exams are not based on CAP413, but ICAO Doc 9432!