POSITION DETERMINATION

A position-coding pattern (3) which extends across a surface and codes a plurality of positions (7a, 7b) on the surface is described. The coding in a first dimension is based on the use of a first and a second string of symbols, each containing a predetermined number of symbols and each having the characteristic that if a specific number of symbols is taken from the first string of symbols, the location of these symbols in the string of symbols is unambiguously determined. By means of displacements between these strings of symbols, a large number of positions can be coded in the first dimension. A third string of symbols of the same type is used for the coding in a second dimension.