Military parlance is the vernacular used within the military and embraces all aspects of service life; it can be described as both a "code" and a "classification" of something. Like many close and closed communities, the language used can often be full of jargon and not readily intelligible to outsiders—sometimes this is for military operational or security reasons; other times it is because of the natural evolution of the day-to-day language used in the various units. For example: "Captain, this situation is 'Scale A'", "Scale A" being an army's parlance for "This situation requires the closest of attention and resources and all members of relevance should be present." The military has developed its own slang, partly as means of self-identification. This slang is also used to reinforce the (usually friendly) interservice rivalries. Some terms are derogatory to varying degrees and many service personnel take some pleasure in the sense of shared hardships which they endure and which is reflected in the slang terms. Military abbreviations The military often use initials and abbreviations of all kinds - partly for security and operational reasons and partly for the simple convenience of their use; like all such things they can be hard to understand for outsiders. A few examples are given below: US Army G.I. - originally stood for "Galvanized Iron" but has come to be interpreted as everything from "General Infantry" (soldiers) to "Government Issue" and "Government Inductee". SHAEF - Supreme Headquarters Allied Expeditionary Force (WWII) AO - Area of Operations Indian Army GD - General Duty - usually indicates the equivalent of G.I. in the US Army. CO - Commanding Officer (of a Major Unit). LC - Line of Control (usually referred to as LoC in non-Military Parlance). British Army HQ - Headquarters CGS - Chief of the General Staff (formerly Chief of the Imperial General Staff (CIGS) - as in Lord Alanbrooke) GCHQ - UK Government Communications Headquarters (Cheltenham) ADC - aide de camp (a military or naval officer who helps an officer of higher rank) OC - Officer Commanding GOC - General Officer Commanding (usually followed by number indicating what rank of General is being mentioned) SIS - Secret Intelligence Service MI8 - British signals intelligence group in World War II. Also known as the Radio Security Service, it tracked radio broadcasts about German bombers during The Blitz. MI9 - Escape & Evasion services (WWII) VC - Victoria Cross