The latest version of the Radio Regulations is the 2016 edition, contained in the Volume 1 - 4 red books. A review of the Radio Regulations has taken place by the World Radiocommunication Conference 2015 (WRC-15).
Table of Contents of the Radio Regulations
| Volume 1 | The Articles |
| Volume 2 | The Appendices |
| Volume 3 | The Resolutions and Recommendations |
| Volume 4 | ITU-R Recommendations incorporated by reference |
The body of the text is divided in to Chapters, Articles and Provisions; then come the Appendices, lastly the Resolutions - RES and Recommendations - REC. The official way of referring to a provision is "The provisions of No. 9.21 " and to an appendix "Appendix 4 of the Radio Regulations", and it is this formulation which should be used in official documents. However, one often sees "No. 9.21" and "AP 4" for short.
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