Workers in this unit group prepare technical drawings and maps and copy drawings and paintings onto printing plates. Their functions include: preparing working drawings from designers' sketches and specifications for such purposes as manufacture and installation of machinery and equipment or for construction of buildings, bridges, dams, roads and other civil engineering projects; preparing topographical, political, economic, nautical and other maps and charts from survey and other data; drawing technical illustrations for reference works, brochures and technical manuals dealing with assembly, installation, operation, maintenance and repair of machinery and other equipment; copying drawings and paintings onto stone or metal plates for printing.