displayed: The typical commander ranks shown in the table are for illustration. Neither the actual rank designated for a particular unit's commander, nor the rank held by the incumbent commander alters the appropriate symbol. For example, units are periodically commanded by an officer junior to the authorised commander grade, yet a company under the command of a Lieutenant (U.S.) or Captain (Commonwealth) is still indicated with two vertical ticks. Likewise, some peculiar types of companies and detachments are authorised a Major, Lieutenant Colonel (personnel services companies) or Colonel (some types of judge advocate detachments); the company or detachment is nevertheless indicated with, respectively, one vertical tick or three dots. While in Commonwealth armies, the regiment as a tactical formation does not normally exist, in some cases a regimental sized (i.e. larger than battalion and smaller than brigade) Task Force may exist where the operational requirement exists. These formations may be commanded by Colonels. Note that, for brigades and higher, the number of Xs corresponds to the number of stars in the United States military's insignia for the typical general officer grade commanding that size unit. For example, a division is capped with XX and is usually commanded by a major general the American insignia for which is two stars. Equipment icons Equipment icons are "frame optional". Installation icons Symbol modifiers APP-6A stops with field AB. MIL-STD-2525B and 2525B Change 1 add a number of other modifiers. Graphic modifiers Echelon (field B) Identifies command level (see Unit sizes, above). Task force (field D) Identifies a unit as a task force. It may be used alone or in combination with Echelon, like so: Frame shape modifier (field E) A short textual modifier that completes the affiliation, battle dimension, or exercise description of an object ("U", "?", "X", "XU", "X?", "J" or "K"). It is treated as a graphic modifier, however. Direction of movement (field Q) A fixed-length arrow that identifies the direction of movement or intended movement of an object. It emanates from the symbol's centre except in the ground domain, where it is hooked to a short offset, straight down from the symbol's base centre (see diagram). Mobility indicator (field R) Depicts the mobility of an object (see Mobility, below). It is used only with equipment. Headquarters staff or offset location (field S) Identifies a unit as a headquarters, or indicates the object's actual location on the map when it has