text: Chapter 7
  that is not the primary avenue where the enemy is expected to attack (ADP 3-90). Assigned when more than
  one avenue of approach into a unit’s area of operations. A subsequent positionis a position that a unit expects
  to move to during the course of battle (ADP 3-90). Subsequent positions can have primary, alternate, and
  supplementary positions associated with them.
  7-103. In accordance with the mission variables, units can conduct survivability moves between their
  primary, alternate, and supplementary positions. A survivability move is a move that involves rapidly
  displacing a unit, CP, or facility in response to direct and indirect fires, the approach of a threat or as a
  proactive measure based on intelligence,meteorological data,and risk assessment of enemy capabilities and
  intentions (ADP 3-90). A survivability move includes those based on the impending employment of weapons
  of mass destruction (WMD).
  7-104. Astrong pointis a heavily fortified battle position tied to a natural or reinforcing obstacle to create
  an anchor for the defense or to deny the enemy decisive or key terrain (ADP 3-90). A strong point implies
  retention of terrain to control key terrain and blocking,fixing,or canalizing enemy forces. Defending units
  require permission from the higher headquarters to withdraw from a strong point. All combat, maneuver
  enhancement,and sustainment assets within the strong point require fortified positions. In addition,extensive
  protective and tactical obstacles are required to provide an all-around defense. (See figure 7-9.)
  Figure 7-9. Strong point placement
  7-105. As a rule of thumb, a minimally effective strong point requires a one-day effort from an engineer
  unit the same size as the unit defending the strong point. Organic BCT engineers lack sufficient capacity to
  create a strong point within a reasonable amount of time;additional engineer assets from echelons above the
  BCT are required. Once the strong point is occupied,all units and equipment not essential to the defense are
  displaced from the strong point. This includes nonessential staff and elements from the forward support
  company(FSC). (SeeFM 3-90-1 for additional information.)