Today I have published a series of pages that contain covernames associated with the Communications Security Establishment (CSE), Government Communications Headquarters (GCHQ), and Government Communications Security Bureau (GCSB). Each of the pages lists covernames which are publicly available as well as explanations for what the given covernames refers to, when such information is available. The majority of the covernames listed are from documents which were provided to journalists by Edward Snowden, and which have been published in the public domain. A similar listing concerning the NSA’s covernames is forthcoming.
You may also want to visit Electrospaces.net, which has also developed lists of covernames for some of the above mentioned agencies, as well as the National Security Agency (NSA).
All of the descriptions of what covernames mean or refer to are done on a best-effort basis; if you believe there is additional publicly referenced material derived from CSE, GCHQ, or GCSB documents which could supplement descriptions please let me know. Entries will be updated periodically as additional materials come available.