A military unit cover designator (MUCD, MUCK-dee, Chinese: 部队代号; pinyin: bùduì dàihào) is a unique five-digit number used by the People's Liberation Army of the People's Republic of China to externally identify military units. MUCDs are used externally to protect the identity of units, while a true unit designator (TUD, Chinese: 部队番号; pinyin: bùduì fānhào) is used internally as they plainly identify the unit and its function.
An example, a bomber aircraft regiment in the People's Liberation Army Air Force (PLAAF) 8th Air Division may be known by its TUD, '22nd Air Regiment', or by its MUCD, 'Unit 95183'. The unit's TUD is used by members of the regiment, in common discourse, and among defense analysts, while the MUCD is used on stationery letterheads, newspapers, banners, magazine articles, and signs at the entrance to military facilities.[1]
Some units, namely those conducting sensitive and secretive operations like those of the Third Department (Operations) of the Joint Staff Department, may only be known by their MUCD as their TUD has not been discovered. Popular examples include Unit 61398 and Unit 61486.[2]