Abstract
The continuing reduction in the price of graphics terminals has led to greater interest in graphics and computer aided design. This trend has in turn focussed attention on methods of modelling graphical data using programming languages and databases. This paper presents a method of defining, analyzing and transforming graphical data using an extended APL notation. The fundamental extension this notation makes to APL is to allow the items in an APL array to have a user defined data structure. A consequence of this extension is that the items in an array can now represent graphical entities such as circles, lines, points etc. In conventional APL an item in an array must be either a number or a character. In this extended notation an item in an array might be a structure designed to represent a point, or a circle, or any other entity.