SNNS originally was not designed to handle units whose location carry semantic information. Therefore some points have to be taken care of when dealing with SOMs. For learning it is necessary to pass the horizontal size of the competitive layer to the learning function, since the internal representation of a map is different from its appearance in the display. Furthermore it is not recommended to use the graphical network editor to create or modify any feature maps. The creation of new feature maps should be carried out with the BIGNET (Kohonen) creation tool (see chapter ).