In the British military, Sunray was the radio code (technically the Appointment Title) used to refer to the boss -- the OC or unit leader. The second-in-command is Sunray Minor; if clarification is needed, the first-in-command maybe referred to as Sunray Major.
Sunray is complimented by Moonbeam, the Chief of Staff. While the titles were not especially sky-themed, they also included Starlight for medical, and Skypilot for the padre.
The Sunray title is useful because it identifies the most senior person available, but it doesn't given any specific information to enemy agents that might be monitoring the frequency. Most specifically, it doesn't give the rank of the person leading the formation, which might be useful in determining the size and perhaps role of the force.
Sunray is also used humorously to refer to spouses; e.g., "Long Haired Sunray".
Appointment titles were replaced with BATCO codes in the 1980s, and most appointment titles are now informal and infrequently used. Sunray and Sunray Minor live on in many Commonwealth forces.