Main Station: A main station is a point on a chain survey where two sides of a traverse or triangle meet. These stations dictate the boundaries of the survey and are designated by capital letters such as A, B and C.
Tie station or sub-station: A tie station is a station on a survey line that joins the main stations. These are helpful in locating the interior details of the area being surveyed and are designated by lowercase letters such as a, b and c.
Main Survey Line: The chain line connecting two main survey stations is called main survey line. AC represents an important survey line.
Tie Line or Sub Line: A chain line connecting two tie stations is called a tie line, eg jk. It is also called the auxiliary line. These are provided to locate internal details, which are far from the main lines.
Baselines: This is the longest main survey line on fairly level ground and passes through the center of the area. This is the most important line because it determines the direction of all other survey lines with respect to this line.
Check Lines: A check line or proof line is a line provided to check the accuracy of field work. The measured and calculated (out-of-plan) length of the check line must be the same.
Offset: This is the distance of the object from the survey line. It can be vertical or diagonal.
Chain: It is the distance from the starting point to a well-defined point. In chain surveying this is usually referred to as the distance in feet of the offset from the starting point on the chain line.
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