Angle of sight
The angle between the line of sight and the horizontal plane. The angle is said to be plus when the target is above the horizontal plane and minus when the target is below it.
Crest clearance angle
The angle by which the barrel must be raised above the line of sight to the crest to ensure that all the bullets will clear the crest.
Deflection
A lateral displacement of the lines of any, or all, guns.
Direct fire
When the gun is laid directly on the target by means of the backsight and foresight.
Fixed line
A term denoting that measures have been taken for maintaining elevation and direction in darkness, etc, to ensure that fire will fall on the pre-arranged target area.
Flanking fire
Fire applied across the front of a locality occupied by own troops, or, if they are advancing, at an angle to their line of advance.
Ground angle
The angle between the line of sight to the target and the line of sight to own troops when using overhead fire.
Group commander
An officer or NCO commanding two or more machine gun sections.
Indirect fire
When a gun is laid to hit a target by other means than by laying on it direct.
Line of fire
The direction of the target from the gun.
Minimum clearance
A term used to denote the minimum height of the centre bullet of the cone above the heads of our own troops for the latter to be safe.
Near limit of arc
The nearest line across the arc of fire on which fire may be required.
Overhead fire
Fire passing over the heads of our own troops.
Pivot gun
The gun used as a basis for a calculation.
Quadrant angle
The angle which the axis of the barrel makes with the horizontal plane.
Quadrant elevation
The quadrant angle expressed in terms of a range and an angle of sight.
Registering
The recording of the direction and elevation necessary to hit any given target found by ranging.
Safety angle for flanking fire
The minimum lateral angle by which fire must clear our own troops for them to be safe.
Safety angle for overhead fire
The minimum angle which must be included between the axis of the barrel and the line of sight to own troops to ensure their safety under overhead fire.
Tangent angle
The angle which the axis of the barrel makes with the line of sight.
Zero line
A line of reference on which all guns are parallel and from which switches are measured.
| DP | Drill pattern. |
| IA | Immediate action. |
| MMG | Medium machine gun. |
| MPI | Mean point of impact. |
| OP | Observation post. |
| RAP | Regimental aid post. |
| RV | Rendezvous. |
| QE | Quadrant elevation. |
| Manual Index |
