CAP 413 – Radiotelegraphy Manual (Edition 21, Amendment 1) (link)
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.
In addition to minor editorial and administrative corrections, the following amendments to technical content have been incorporated:
– Conditional line-up
– Squawk with altitude
– Level information within traffic information messages
– ATSOCAS request message content
– PAN PAN MEDICAL details
– Radio Mandatory Zones
The amended CAP 413 will become effective on 14th November 2013.
Source: CAA