Glossary

You might find the following corner descriptions on a plat drawing.

  • CMF - Concrete monument found
  • IPF - Iron pipe found
  • IRF - Iron rod found
  • L.O.D. - Limit of Disturbance. The area had to be cleared, graded, etc.
  • B.R.L. - Building Restriction Line
  • PK nail - A surveyor's nail that marks a survey point. See also hub and tack.
  • SIR - Set Iron Rod

accuracy: degree of conformity with a standard. Accuracy relates to the quality of a result, and is distinguished from precision, which relates to the quality of operation by which the result is obtained. see Accuracy and Precision for further information.

easement: areas of land owned by the property owner, but in which other parties, such as utility companies, may have limited rights granted for a specific purpose.

encroachment: a structure or part of a structure that occupies the property of another.

encumbrance: an interest or partial right in real property which diminished the value of ownership, but does not prevent the transfer of ownership. Mortgages, taxes and judgments are encumbrances known as liens. Restrictions, easements, and reservations are also encumbrances, although not liens.

error: the difference between a measured value and the true value. Error in measurement is inherent, but is separate and distinct from a blunder (a mistake).

exception: from a title insurance policy, portions of the land containing encumbrances and in which free and clear title is subject to certain conditions. From a legal description, portions of land which are included in the description of a larger parcel of land but then excluded from it by a subsequent legal description.

improvement: usually some sort of man-made structure, although perhaps not always a literal "improvement".

legal description: a method of describing a particular parcel of land in such a way that it uniquely describes the particular parcel and no other. A legal description may be a simple reference to a lot as shown on a subdivision plat, or be described by metes and bounds. To be adequate, it should be sufficient to locate the property without oral testimony.

measurement: an estimated value that is, by its nature, subject to error. A person can count (an absolute value) one hundred beans and get the same quantity as someone else counting one hundred beans. However, if two people each measure (an estimated value) a cup of beans, it is likely that they will have a different quantity of beans. Two surveyors measuring the same distance may obtain different values. Both of the values should be similar, but they will only approach the true theoretical value through repetition and statistical analysis.

monument: an object placed to mark the physical location of a position. A property corner monument is often a length of iron rod driven vertically into the ground so that the top is at or below natural grade. A cap identifying the registration number of the surveyor responsible for placing the monument may be placed atop the monument.

offset: in boundary: a point located at the extension of a line and marking the direction of the line. An offset monument may be placed on the extension of a line because the offset position can provide a more durable monument. A common practice is to place offset monuments in a sidewalk or curb head, as these monuments are less likely to be disturbed than a monument marking the actual position. in construction: a short distance usually measured at a right angle to a line, to preserve the position of the line when it is anticipated that points marking the line itself would be disturbed.

precision: the degree of refinement in the performance of an operation, or the degree of perfection in the instruments and methods used when making measurements. An indication of the uniformity or reproducibility of a result. Precision relates to the quality of an operation by which a result is obtained, and is distinquished from accuracy, which relates to the quality of the result. see Accuracy and Precision for further explanation.

right-of-way: a parcel of land granted by deed or easement for construction and maintenance according to a designated use. This may include highways, streets, canals, ditches, or other uses.

subdivision plat: a legal instrument intended to take a large parcel of land and divide it into smaller parcels of land. A subdivision plat may also create public rights-of-way or easements, and is usually filed with the public real estate records of the county.

surveying: a blend of several disciplines, from mathematician and law scholar, to expert measurer and translator. By interpreting the legal description and applying the science of measurement, the surveyor translates a legal description or construction plans into tangible positions on the ground. These positions then become the basis for construction or for the establishment of a particular location, possibly to show lines of ownership or to document change over time.

title commitment: a commitment to provide title insurance to a parcel of land. The surveyor is interested in the legal description and the exceptions.

tolerance: a mathematical term indicating the allowable variation from a standard or from specified conditions. It is an indication of the accuracy and the precision of a measurement.

Surveying Terms

  • Acre - The (English) acre is a unit of area equal to 43,560 square feet, or 10 square chains, or 160 square poles. It derives from a plowing area that is 4 poles wide and a furlong (40 poles) long. A square mile is 640 acres. The Scottish acre is 1.27 English acres. The Irish acre is 1.6 English acres.
  • Azimuth - The number of degrees from north (or other reference direction) that a line runs, measured clockwise.
  • Benchmark - A survey mark made on a monument having a known location and elevation, serving as a reference point for surveying.
  • Call - Any feature, landmark, or measurement called out in a survey. For example, "two white oaks next to the creek" is a call.
  • Chain - Imperial = 4 poles = 22 yards. Attempt by Edmund Gunter (U.K. 1620's) to make land measure, a decimal system. His 66 foot chain had 100 links. , but possibly variant by locale. See also Rathbone's chain. The name comes from the heavy metal chain of 100 links that was used by surveyors to measure property bounds.
  • Conditional line - An agreed line between neighbors that has not been surveyed, or which has been surveyed but not granted.
  • Corner - The beginning or end point of any survey line. The term corner does not imply the property was in any way square.
  • Declination - The difference between magnetic north and geographic (true) north. Surveyors used a compass to determine the direction of survey lines. Compasses point to magnetic north, rather than true north. This declination error is measured in degrees, and can range from a few degrees to ten degrees or more. Surveyors may have been instructed to correct their surveys by a particular declination value. The value of declination at any point on the earth is constantly changing because the location of magnetic north is drifting.
  • Foot - Imperial = 12 inches. Based on the length of the human foot.
  • Engineer's Chain - A 100 foot chain containing 100 links of one foot apiece.
  • Furlong - Unit of length equal to 40 poles (220 yards). Its name derives from "furrow long", the length of a furrow that oxen can plow before they are rested and turned. See Gunter's chain.
  • Gunter's Chain - Unit of length equal to 66 feet, or 4 poles. Developed by English polymath Edmund Gunter early in the 1600's, the standard measuring chain revolutionized surveying. Gunter's chain was 22 yards long, one tenth of a furlong, a common unit of length in the old days. An area one chain wide by ten chains long was exactly an acre. In 1695 Queen Elizabeth I had the mile redefined from the old Roman value of 5000 feet to 5280 feet in order for it to be an even number of furlongs. A mile is 80 chains.
  • Landmark - A survey mark made on a 'permanent' feature of the land such as a tree, pile of stones, etc.
  • Line Tree - Any tree that is on a property line, specifically one that is also a corner to another property. Link - Unit of length equal to 1/100 chain (7.92 inches).
  • Metes and Bounds - An ancient surveying system that describes a parcel of land in terms of its relationship to natural features and adjacent parcels.
  • Monument - A permanently placed survey marker such as a stone shaft sunk into the ground.
  • Plat - A drawing of a parcel of land.
  • Perch - See pole.
  • Point - A point of the compass. There are four cardinal points (North, South, East, West), and 28 others yielding 32 points of 11.25 degrees each. A survey line's direction could be described as a compass point, as in "NNE" (north northeast). To improve precision, the points would be further subdivided into halves or quarters as necessary, for example, "NE by North, one quarter point North". In some areas, "and by" meant one half point, as in "NE and by North".
  • Point of Beginning - The starting point of the survey
  • Pole - Unit of length and area. Also known as a perch or rod. As a unit of length, equal to 16.5 feet. A mile is 320 poles. As a unit of area, equal to a square with sides one pole long. An acre is 160 square poles. It was common to see an area referred to as "87 acres, 112 poles", meaning 87 and 112/160 acres.
  • Rod - See pole
  • Tie line - A survey line that connects a point to other surveyed lines.
  • Traverse - 1) any line surveyed across a parcel, 2) a series of such lines connecting a number of points, often used as a base for triangulation.
  • Witness Tree - Generally used in the U.S. public land states, this refers to the trees close to a section corner. The surveyor blazed them and noted their position relative to the corner in his notebook. Witness trees are used as evidence for the corner location.

Surveying Slang

Surveying, like any profession, has its special terms and slang.

  • Cut line - To clear vegetation for a line of sight between two survey control points.
  • Dummy or dummy-end - The base or zero end of a tape or chain, as in "hold dummy at the face of the curb."
  • EDM - Electromagnetic Distance Measurement device, the instrument used by modern surveyors that replaces the use of measurement chains. It determines distance by measuring the time it takes for laser light to reflect off a prism on top of a rod at the target location.
  • Glass - The EDM prism.
  • Gun - Originally, a transit, but potentially any measurement instrument in use, e.g. theodolite, EDM, or Total Station.
  • Hub and Tack - A 2" by 2" stake that is set in the ground and that contains a nail ("tack") that precisely marks the point being set.
  • Legs - Tripod
  • Rodman - The person holding the rod with the EDM prism. This person is the modern version of a chain carrier or chain man.
  • Shoot - Measure distance with an EDM
  • Spike - Usually a 60 penny nail used to mark survey points in hard ground.
  • Tie - To locate something with the transit or other measuring device.
  • Turn - The rodman is told to stay in place while the gun or level is moved to a new location.