OBLIQUE FIRE- Fire delivered from a direction that is diagonal to the long axis of the target; or fire delivered on an enemy from a direction that is between his front and flank.

OBSERVATION POST (OP)- A vantage point from which enemy activity in front of the FEBA is observed.

OBSTACLE- Any barrier-natural or artificial-that stops or impedes the movement of a unit.

OPERATION PLAN OR ORDER- A combat plan or order dealing with tactical operations and setting forth the mission of the unit; it deals with the commander's decision, plan of action, and such details as to the method of execution as will ensure coordinated action by the whole command.

OPTICAL SIGHT- A sight having lenses as contrasted with one having an aperture or open sight.

ORGANIC- Assigned to and forming an essential part of a military organization.

ORIGINATOR- The command by whose authority a message is sent.

OUTGUARD- The principal security element of a combat outpost.

OUTPOST- A stationary body of troops placed at some distance from the main body while at a halt or in a defensive position. These troops protect the main body from surprise, observation, or annoyance by enemy ground forces.

OUTPOST LINE OF RESISTANCE- A line passing through the forward edge of the outpost positions and designed to coordinate the fires of the elements of the outpost and its supporting fires.

OVERHEAD FIRE- Fire delivered over the heads of friendly troops.

OVERLAY- A transparent or translucent medium upon which special military information has been plotted at the same scale of a map, photograph, or other graphic.

PACE- The length of a full step in quick time; 30 inches.

PARTISAN- A devoted adherent to a cause generally nationalistic in nature; the adherent mayor may not be an armed combatant and is not normally a member of an organized military force.

PASSAGE OF LINES- A rearrangement of units in which the rear unit moves forward through the already established line, while the replaced unit remains in position or moves to the rear.

PATROL- A detachment sent out by a larger unit for the purpose of gathering information or carrying out a destructive, harassing, mop up, or security mission.

PA- A part of the feeding device on a machine gun that permits feeding of the ammunition belt into the weapon; it holds the belt securely so it does not move in reverse direction.

PENETRATION- An attack that puts the main attacking force through the enemy's principal defensive position.

PHASE LINE- A line used for control and coordination of military operations; it is usually a terrain feature extending across the zone of action.

PIECE- Any firearm.

PLUNGING FIRE- Fire that strikes the ground at a sharp angle.

POINT- The security element that forms the leading element of an advance guard or the rear element of an advance guard or the rear element of the rear guard.

POINT OF DEPARTURE- The point on the line of departure at which an attacking force in column crosses.

POINT OF DRESS- The point toward which all elements of a unit establish their alignment.

POLITICAL WARFARE- Aggressive use of political means to achieve national objectives.

POSITION- The location of a gun, unit, or individual from which fire can be delivered upon a given target.

POST- The prescribed limits of a sentry's respon-sibility.

PREARRANGED FIRE- Supporting fire for which the fire data is prepared in advance. It is delivered on a time schedule or on call from the support troops.

PRINCIPAL DIRECTION OF FIRE (PDF)- A specific direction within the sector of fire of a flat-trajectory weapon, which is designated as its primary fire mission. Within a rifle platoon, automatic weapons are assigned a PDF. Units are not assigned PDFs nor can a weapon be assigned more than one PDF.

PROBABLE LINE OF DEPLOYMENT- The location on the ground where the commander of a force plans to complete final deployment before moving out with squads as skirmishers.

PROPAGANDA- Any information, ideas, doctrines, or special appeals spread to influence the opinions, emotions, attitudes, or behavior of any specified group to benefit the sponsor, either directly or indirectly.

PROPELLING CHARGE- An explosive that throws the projectile from a gun.

PROTECTIVE FIRE- Fire delivered by supporting weapons and directed against the enemy for the purpose of hindering his fire or movement against friendly attacking units.

QUICK TIME- Cadence at 120 steps (12, 15, or 30 inches in length) per minute.

RADIO CHANNEL- A band of adjacent frequencies having sufficient width to permit its use for radio communications.

RAID- An operation, usually small scale, involving a swift penetration of hostile territory to secure information, confuse the enemy, or destroy his installations. The operation ends with a planned withdrawal upon completion of the assigned mission.

RANK- A line of men or vehicles placed side by side; officer's grade or position.

REAR- The direction away from the enemy.

REAR AREA- The area in the rear of the combat and forward areas.

REAR GUARD- The security element that follows and protects the rear of a marching force.

REBELLION- Organized, armed, open resistance to the authority or government in power.

RECONNAISSANCE PATROL- A patrol whose mission is to gain information about the enemy and the terrain.

REGISTRATION- The adjustment of fire to determine firing corrections.

RELAY- A transmission forwarded through an intermediate station.

RELEASE POINT- A point at which a higher command releases control of a unit to its commander.

RELIEF OF FRONT-LINE UNITS- A rearrangement of units in which the rear unit moves forward to the battle position and occupies the defensive positions there; at the same time the forward unit in the battle position relinquishes these positions and moves to the rear.

REPEAT- A command or request to fire again the same number of rounds with the same method of fire.

RESERVE- An element of the battalion or higher unit held initially under the control of the commander as a maneuvering element to influence future action.

RESERVE AREA- The area that extends from the rear of the forward defense area to the rear of the battle area. The RESERVE FORCE is located in the reserve area.

RETIREMENT- An operation in which a force withdraws without enemy pressure to avoid combat under the existing situation.

RETROGRADE MOVEMENT- Any movement of a command to the rear, or away from the enemy, whether forced by the enemy or voluntary, including a withdrawal, retirement, or delaying action.

REVERSE SLOPE- Any slope that descends away from the enemy.

REVOLT- A casting off of allegiance or a refusal to submit to established authority.

REVOLUTION- A rebellion that succeeds in overthrowing an old government and establishing a new one.

RIGHT (LEFT) FLANK- The extreme right (left) element or edge of a body of troops in relation to the enemy, regardless of the direction in which the body of troops is facing.

ROADBLOCK- A barrier or obstacle to block or limit the movement of hostile vehicles along a road.

ROUTE MARCH- The advance in column on roads.