Used to analyze terrain and weather (previously known at OCOKA)
Observation and fields of fire: The company commander (or platoon leader) must identify locations along each avenue of approach that provide clear observation and fields of fire for both the attacker and the defender. He analyzes the area surrounding key terrain, objectives, engagement areas, and obstacles. He locates IV lines (terrain that inhibits observation from one point to another) and assesses the ability of the attacking force to overwatch or support movement (with direct fire). In analyzing fields of fire, he focuses on both the friendly and enemy potential to cover terrain (especially avenues of approach and key terrain) with direct fires. Additionally, he must identify positions that enable artillery observers to call indirect fire. Whenever possible, he conducts a reconnaissance of the ground from both enemy and friendly perspectives. He might conduct this reconnaissance personally, by map, or with his subordinate units. This reconnaissance helps him to see the ground in a more objective manner and to see how the ground affects both enemy and friendly forces.
Avenues of approach: An avenue of approach is an air or ground route of an attacking force leading to an objective or key terrain. Avenues of approach are classified by type (mounted, dismounted, air, or subterranean), formation, and speed of the largest unit that can travel along it. First, the company commander (or platoon leader) must identify mobility corridors, if not provided by the higher headquarters. Mobility corridors are areas where a force can move in a doctrinal formation at a doctrinal rate of march; they are classified by type and size of force and formation employed.
Key and decisive terrain: The company commander (or platoon leader) must identify key terrain. Key terrain is any location or area of which the seizure, retention, or control affords a marked advantage to either combatant. It is a conclusion rather than an observation; a prominent hilltop overlooking an avenue of approach, for example, may or may not be key terrain. Even if the hill offers clear observation and fields of fire, it is of no marked advantage to the unit that controls it if the opposition can easily bypass it on another avenue of approach. On the other hand, if the hilltop affords cover and concealment, observation, and good fields of fire on multiple avenues of approach or is the only avenue of approach in the area, the terrain offers a definite advantage to whoever controls it. Furthermore, an area where several trails converge may be key terrain for an antiarmor platoon, whereas an area in which several battalion-size avenues of approach join may prove key for an antiarmor company.
Obstacles: The leader first identifies existing and reinforcing obstacles in his area of operation that limit mobility with regards to the mission. These include both existing obstacle (natural obstacles to include preexisting buildings) and reinforcing obstacles (minefields, wire obstacles etc).
Cover and concealment: The company commander (or platoon leader) looks at the terrain, foliage, structures, and other features along avenues of approach and on objectives or key terrain to identify sites that offer cover (protection from the effects of direct and indirect fire) and concealment (protection from observation). In the defense, weapon positions must be both lethal and survivable, and effective cover and concealment is just as vital as clear fields of fire.