A successfully developed design system which provides an on‐line interactive facility for the application of engineering drawings is described. A set of processing questions as well as a set of control functions are supplied to support man‐machine interactive construction and maintainence of picture data. A vector‐valued parametric form together with the basic operations of translation, rotation, and scaling are integrated into a standard form for generating picture primitives. Also, a B‐tree structure is used to minimize disk access times so that data base file organization of the design system can handle huge amount of picture records.