ADP 3-90, page 96

Glossary Glossary-10 ADP 3-90 31 July 2019 *retirement When a force out of contact moves away from the enemy. *retrograde (Army) A type defensive operation that involves organized movement away from the enemy. *route reconnaissance A type of reconnaissance operation to obtain detailed information of a specified route and all terrain from which the enemy could influence movement along that route. rules of engagement Directives issued by competent military authority that delineate the circumstances and limitations under which United States forces will initiate and/or continue combat engagement with other forces encountered. (JP 3-84) *science of tactics The understanding of those military aspects of tactics—capabilities, techniques, and procedures—that can be measured and codified. *screen A type of security operation that primarily provides early warning to the protected force. *section (Army) A tactical unit of the Army and Marine Corps smaller than a platoon and larger than a squad. *security area That area occupied by a unit’s security elements and includes the areas of influence of those security elements. *security operations Those operations performed by commanders to provide early and accurate warning of enemy operations, to provide the forces being protected with time and maneuver space within which to react to the enemy, and to develop the situation to allow commanders to effectively use their protected forces. *sequential relief in place Occurs when each element within the relieved unit is relieved in succession, from right to left or left to right, depending on how it is deployed. *simultaneous relief in place Occurs when all elements are relieved at the same time. situational understanding The product of applying analysis and judgment to relevant information to determine the relationships among the operational and mission variables. (ADP 6-0) special reconnaissance Reconnaissance and surveillance actions conducted as a special operation in hostile, denied, or diplomatically and/or politically sensitive environments to collect or verify information of strategic or operational significance, employing military capabilities not normally found in conventional forces. (JP 3-05) *squad A small military unit typically containing two or more fire teams. *staggered relief in place Occurs when a commander relieves each element in a sequence determined by the tactical situation, not its geographical orientation.