**ANGLE** – a value expressed in degrees, or parts, being a fractional or whole value of a circle which contains 360°, based on the ancient calculation of the number of days in a lunar year.

**AZIMUTH** – from the Arabic *al-samt*, a direction expressed by degrees, or parts, referenced from a specific orientation. Generally this is a 0° to 360° value based on a 0° north __or__ south in a clockwise direction.

**BACKSIGHT** – the point (or line) from which observations at a **TRAVERSE POINT** are referenced.

**BASIS OF BEARING** – the specified reference of a survey, legal description or traverse. It may be observed directly, such as with a sighting of the Sun or stars or between two known marks, or calculated by **INVERSE** between sighted objects.

**BEARING** – a direction expressed by degrees, or parts, referenced from north or south and heading toward the east or west, e.g. north 50° east, north 30° west, south 12° west, south 62° east.

**BENCHMARK** – a point of established elevation.

**BENCH RUN** – a series of connected elevation observations to or from a **BENCHMARK**.

**CLOSED TRAVERSE** – a series of observed lines, defined by a common reference, with distances measured and returning to the starting point or **POINT OF BEGINNING**. It is used by surveyors as a series of sides of a closed geometric figure on the ground that may be used as the basis for additional observations or object sightings.

**CONTROL POINT** – a location of known survey value.

**DATUM** – the common reference elevation to which other points are related, such as mean sea level. (For geodetic surveying the datum is also specified for X and Y values.)

**FORESIGHT** – the forward point (or line) to which observations are made from a **TRAVERSE POINT**.

**INVERSE** – the calculated distance and orientation between two objects derived from trigonometric calculation.

**OPEN TRAVERSE** – a series of observed lines that do not return to the **POINT OF BEGINNING**.

**ORIGIN** – the point at which the value of both X and Y equals zero. In plane surveying this is often an unobtainable location and one used merely for the convenience of calculations.

**POINT OF BEGINNING** – the first-occupied **TRAVERSE POINT** of a survey; also the beginning point of a legal description in a deed.

**RANDOM TRAVERSE** – a traverse whose final basis of bearing is derived from observations made during its execution. Most modern surveys are conducted in this manner. The **TRAVERSE POINTS** are set as with convenience of occupation and sighting as paramount.

**TRAVERSE POINT** – the location of an angle or bend in the traverse; also the physical object which represents it such as a nail, a monument, a pipe, a hub, etc..

**TURNING POINT** – the place where rod readings are taken for a continuous bench run.

**X, Y, Z** – the three-dimensional qualities of a point; X is the east-west value from the **ORIGIN**, Y is the north-south value and Z is the elevation referred to the **DATUM**.