This specification is designed to be incorporated into a contract to define the technical performance requirements for the purchase of illustration or picture description data (in contrast to product definition data) in digital form for use in technical illustrations and technical publications. A metafile, as provided in this document, represents illustration data in the form of a conforming metafile. A conforming metafile contains, in device-independent, system-independent, and implementation-independent form, the picture description data represented by the functions invoked through an application program interface. This specification defines the allowable elements and parameters that may be used to compose the picture.