An instrument used to define the relative parallelism of two or more surfaces (usually tooth surfaces) on a cast. It may have an adjustable table on which the cast is mounted that can be used to establish the path of insertion and removal of an appliance. A surveyor is used for a number of purposes, including surveying a diagnostic or master cast, contouring a wax pattern, the placement of intra-coronal attachments and internal rest seats, and the machining of cast restorations. Accessory tools used include a carbon marker to mark the height of the contour and an undercut gauge to measure the undercut depth. The increased use of computer-aided design/computer-aided manufacture (CAD/CAM) for surveying (virtual surveying) may in time replace the physical surveyor.