Linear referencing (also called linear reference system or linear referencing system or LRS), is a reference system in which the locations of features are identified by a relative measure along a linear element, for example a milestone along a road. Each feature is located by either a point (known as a "milepoint") or a line ("segment"). The system is designed so that if a segment of a route is changed only those milepoints on the changed segment need to be updated.
Linear referencing is suitable for management of data related to linear features like roads, railways, oil and gas transmission pipelines, power and data transmission lines, and rivers.
A system for identifying the location of pipeline features and characteristics is by measuring distance from the start of the pipeline. An example linear reference address is: Engineering Station 1145 + 86 on pipeline Alpha = 114,586 feet from the start of the pipeline. With a reroute, cumulative stationing might not be the same as engineering stationing, because of the addition of the extra pipeline. Linear referencing solves this dilemma.
Linear referencing is supported for example by several Geographic Information System software, including: