A new and efficient real time technique to produce a string code description of the contour of an object, such as an (angle, length) (0, s) feature space for the arcs describing the contour, is detailed. We demonstrate the use of such a description for an aircraft identification problem case study. Our (0, s) feature space is modified to include a length string code and a convexity string code. This feature space allows both global and local feature extraction. The local feature extraction follows human techniques and is thus quite suitable for a rule-based processor (as we discuss and demonstrate). Aircraft have generic parts and thus are quite suitable for the model-based description.