In SCAN-3, the set of observations is devided into observation groups. All observation types may appear any number of times. This observation group approach allows both a flexible construction of models and the processing of large numbers of observations in one run. Correlation between two observations from two different observations groups can never be present.
Constraints can be either stochastic or deterministic.
The equations of each observation type have been extended with the appropriate number of similarity parameters to achieve invariance under datum transformation. Testing and reliability measures can be computed in the last two cases. Estimated standard deviations are presented in output. Coordinate triads are connected by means of 3D-similarity transformations. One coordinate triad has to be chosen for the parameters to be estimated in.