Edge of Seal
The term edge of seal (EoS) is used in engineering surveys to denote a point along the edge of the sealed surface of a road.
When re-designing a road it is typically very important to know the exact location, alignment and elevation of the existing roadway, and locating and ascertaining the level of a series of points along the "edge of seal" is/was usually a standard step in most rural engineering road surveys. In the days of manual surveys the abbreviation "EoS" was often recorded in field books and level books if the elevation or location of the edge of seal was picked up.
In urban areas the edge of seal is often immediately adjacent to the lip of the kerb, and the term "lip of kerb" may be used instead of "edge of seal".