Integral point sets over finite fields

We consider point sets in the affine plane Fq where each Euclidean distance of two points is an element of Fq . These sets are called integral point sets and were originally defined in m-dimensional Euclidean spaces Em. We determine their maximal cardinality I(Fq , 2). For arbitrary commutative rings R instead of Fq or for further restrictions as no three points on a line or no four points on a circle we give partial results. Additionally we study the geometric structure of the examples with maximum cardinality.