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Chapter 3 3-6 ADP 3-90 31 July 2019 movement rates based on their mobility characteristics and the terrain surrounding their assembly areas. Commanders consider these different characteristics when establishing an LD to prevent these differences from affecting synchronization. When possible, commanders select an LD that provides cover for the unit’s deployment into a combat formation before crossing the LD. In many cases, an LD is also a line of contact because the unit in contact is conducting the attack from its current positions. OBJECTIVE 3-32. An objective is a location used to orient operations, phase operations, facilitate changes of direction, and provide for unity of effort. An objective can be terrain or force oriented. Terrain-oriented objectives should be easy to recognize. A higher echelon commander uses terrain-oriented objectives to focus the operations of subordinates, focus phase operations, facilitate changes of direction, and provide for unity of effort. Commanders determine force-oriented objectives based on known enemy positions. Commanders may assign intermediate objectives as necessary; however, they generally only assign subordinate commanders their final objectives. POINT OF DEPARTURE 3-33. The point of departure is the point where the unit crosses the line of departure and begins moving along a direction of attack. Units conducting patrols and other operations in a low-visibility environment commonly use a point of departure as a control measure. Like an LD, it marks the point where the unit transitions from movement to maneuver under conditions of limited visibility. PROBABLE LINE OF DEPLOYMENT 3-34. A probable line of deployment is a phase line that designates the location where the commander intends to deploy the unit into assault formation before beginning the assault. Units, primarily at battalion echelons and below, use a probable line of deployment when they intend to cross an LD when they are not in their assault formations. It is usually a linear terrain feature perpendicular to the direction of attack and recognizable under conditions of limited visibility. Units ideally locate the probable line of deployment outside the range that enemy forces can place the attacking force under effective direct fire. RALLY POINT 3-35. A rally point is an easily identifiable point on the ground at which units can reassemble and reorganize if they become dispersed (ATP 3-21.20). Forces conducting a patrol or an infiltration commonly use this control measure. The objective rally point is an easily identifiable point where all elements of the infiltrating unit assemble and prepare to attack the objective. It is typically near the infiltrating unit’s objective; however, there is no standard distance from the objective to the objective rally point. It should be far enough away from the objective so that enemy forces will not detect the infiltrating unit’s attack preparations. SUPPORT BY FIRE POSITION 3-36. A support by fire position is the general position from which a unit performs the tactical mission task of support by fire. The purpose of a support by fire position is to increase the supported force’s freedom of maneuver by placing direct fires on an objective that a friendly force assaults. Commanders select support by fire positions so that the moving assault force does not mask its supporting fires. Support by fire positions are normally located on the flank of the assault force and elevated above the objective. Support by fire positions rarely apply to units larger than company size. TARGET CONTROL MEASURES 3-37. A target is an area designated and numbered for future firing. Target graphic control measures are different for point targets, linear targets, and area targets. To support a maneuver phase, individual point or single targets can combine into a target series or target groups. A group of targets consists of two or more targets on which a force may place simultaneous fires. A series of targets is fired in a predetermined time