denote hostile affiliation. In the other domains (air and space, sea surface and subsurface, etc.), the same color scheme is used. The full set of affiliations is: Pending (P) Unknown (U) Assumed friend (A) Friend (F) Neutral (N) Suspect (S) (assumed hostile) Hostile (H) Exercise pending (G) Exercise unknown (W) Exercise assumed friend (M) Exercise friend (D) Exercise neutral (L) Joker (J) (exercise suspect) Faker (K) (exercise hostile) There are no "assumed neutral" and "exercise assumed neutral" affiliations. These colors are used in phrases such as "blue on blue" for friendly fire, blue force tracking, red teaming, and Red Cells. Battle dimension Battle dimension defines the primary mission area for the operational object within the battlespace. An object can have a mission area above the Earth's surface (i.e., in the air or outer space), on it, or below it. If the mission area of an object is on the surface, it can be either on land or sea. The subsurface dimension concerns those objects whose mission area is below the sea surface (e.g., submarines and sea mines). Some cases require adjudication; for example, an Army or Marine helicopter unit is a manoeuvring unit (i.e., a unit whose ground support assets are included) and is thus represented in the land dimension. Likewise, a landing craft whose primary mission is ferrying personnel or equipment to and from shore is a maritime unit and is represented in the sea surface dimension. A landing craft whose primary mission is to fight on land, on the other hand, is a ground asset and is represented in the land dimension. Closed frames are used to denote the land and sea surface dimensions, frames open at the bottom denote the air/space dimension, and frames open at the top denote the subsurface dimension. An unknown battle dimension is possible; for example, some electronic warfare signatures (e.g., radar systems) are common to several battle dimensions and would therefore be assigned an "Unknown" battle dimension until further discrimination becomes possible. Special forces may operate in any dimension. The full set of battle dimensions is, in ascending order of distance from Earth center: SOF (F) Sea subsurface (U) Sea surface (S) Ground (G) Air (A) Space (P) Other (X) Unknown (Z) The mnemonic for this ordering is "Fuss-Gap". The letter in parentheses is used by the symbol identification coding (SIDC) scheme – strings of 15 characters used to transmit symbols. The