SEARCHING FIRE- Fire distributed in depth bysuccessive changes in elevation of a weapon.

SECTION- A military unit that is smaller than a p latoon and larger than a squad; the basic tactical unit in the weapons platoon of the rifle company.

SECTOR- A clearly defined area that a given unit protects or covers with fire.

SECTOR OF FIRE- A section of terrain designated by boundaries that is assigned to a unit or to a weapon to cover by fire.

SECURITY- Measures taken by a command to protect itself from espionage, observation, sabotage, annoyance, or surprise.

SECURITY AREA- The area forward of the FEBA assigned to a battalion or company. A battalion's security area extends to whatever distance security forces, uncontrolled by the battalion, are employed. A company's security area extends 400 to 500 yards (maximum effective range of small-arms fire) to the most forward extension of the company's lateral boundary.

SHOCK ACTION- Actual hand-to-hand combat between opposing troops; an offensive movement by fast-moving forces in which they tend to overrun the enemy by the force of their own momentum.

SHORT- A spotting or an observation used by a spotter or an observer to indicate that a burst fell SHORT of the TARGET in relation to a line perpendicular to the spotting line.

SITREP- A situation report.

SKETCH- A hasty, pictorial drawing showing only desired map features and objects in relative position; usually for a specific use.

SKIRMISHERS- A line of troops in extended order during a tactical exercise or attack.

SNAP- In commands or signals, the quality that inspires immediate response.

STATIC- Any electrical disturbance caused by atmospheric conditions. Interferes with radio com-munications.

STEP- The distance from heel to heel between the feet of a marching man; normally 30 inches.

SUPPLEMENTARY POSITION- An extra position other than the designated primary or alternate position.

SUPPLY POINT- A point where supplies are issued (for example, depot, railhead, truckhead, airhead, or navigation-head).

SUPPORT- The action of a force that aids, protects, complements, or sustains another force according to a directive requiring such actions; a unit that helps another unit in battle; the reserve of a rifle company or platoon in the attack or defense; an element of a command that assists, protects, or supplies other forces in combat.

SUPPORTING FIRE- Fire delivered by weapons of supporting units to assist or protect a unit in combat.

SUPPORTING WEAPONS- Weapons other than those with which a rifle unit is normally equipped.

TERRAIN- An area of ground, considered as to its extent and natural features, in relation to its use in a particular operation.

TOPOGRAPHICAL CREST- The highest point on elevated terrain.

TRAJECTORY- The path described by a projectile in flight.

TRAVERSING FIRE- Fire distributed in width by successive changes in direction of a weapon.

UNDERGROUND- A civilian organization that supports the resistance movement through covert (secret) actions. Such actions include intelligence collection, subversion, sabotage, terror, assassination, and dissemination of propaganda in areas denied to the guerrilla force.

UNIT-Any military force having a prescribed organization.

UNIT OF FIRE- A unit of measure for ammunition supply. It represents a specific number of rounds of ammunition per weapon.

WEDGE FORMATION- A tactical formation in the form of a V with the point toward the enemy; a formation with elements in echelon to the right and left rear. Also called a V-formation.

WITHDRAWAL- A movement whereby a force disengages from an enemy force according to the will of the commander.

ZONE OF ACTION- Ageographical area within which a military unit is to act, and for which it is responsible.

ZONE OF FIRE- An area into which a particular unit delivers, or is prepared to deliver, fire.