Individuals who measure and map the earth's surface and establish official land, air space and water boundaries. They write descriptions of land for deeds, leases and other legal documents; define airspace for airports; and measure construction and mineral sites. Other surveyors provide data relevant to the shape, contour, location, elevation or dimension of land or land features. Land surveyors manage survey parties who measure distances, directions and angles between points and elevations of points, lines and contours on, above and below the earth's surface. They plan the fieldwork, select known survey reference points and determine the precise location of important features in the survey area. Surveyors research legal records, look for evidence of previous boundaries and analyze the data to determine the location of boundary lines. They record the results of surveys, verify the accuracy of data and prepare plots, maps and reports. Included are surveying technicians who assist land surveyors by operating survey instruments, collecting information in the field and performing computations and computer-aided drafting in offices.