A “picture pattern” is a description of a picture or class of pictures in terms of its components and their interrelationships. In the ESP³ language and pattern recognition system, a line drawing is searched for occurrences of subpictures which match a given picture pattern. In “inexact-match mode”, the search routines are lenient in their interpretation of a pattern. Shapes of primitives need not be perfect, and predicates have built-in tolerance. Thus a simple pattern can be used to match a wide variety of noisy or distorted pictures. Inexact-match mode has been added to an experimental implementation of ESP³.⁽¹³⁾ The system has successfully matched a number of simple patterns such as alphabetic characters and has also located objects in some more complex line drawings such as a table and chairs scene.