Introduction} This document describes the Virtual Raster Display Interface, (VRDI). The document contains an overview of the basics behind this package, an overview of display processors, guidelines for effective use of the package, and a detailed description of each routine that is available to an applications programmer. The MIPL Virtual Raster Display Interface is a software package that allows display oriented application programs to be written for a variety of display devices using a set of common routines. Its goal is to provide a uniform operating environment not only for an application programmer, but for the user as well. The programmer is able to write programs without being concerned with the specifics of the device for which the application is intended. \cleardoublepage