Sometimes we find that the message area or certain aspects of it are best depicted by using an arbitrary sign. Such a sign either makes use of an established code or convention for its representation as symbols, or these conventions are required to be worked out afresh. The repeated application of this over a period of time itself makes it recognisable enough for the user, and this process enables him to learn these conventions. The way to generate this category of representations would be to uncover an existing convention that could be used for adoption and modification; or, by converting certain existing associations into a convention. Examples of this practice are the use of red cross as a sign for medical aid; or the use of an outline form (filled in white) to denote the hospital staff and facilities; as against the use of filled forms to depict the patients and the general public. These representations have a tendency to be contextually dependent, and to that extent are restrictive in their application. 

Having semantically articulated the images necessary for the visual representation of a message area, we now turn to the stage where we begin to convert all these alternatives into simple drawings. Upon which, this bank of possible solutions are subject to evaluation in terms of the responses generated among the users. The results are then tabulated and out of the whole set, two or three representations, which are considered semantically more appropriate solutions than the others are further taken up for the following phase of the process. The above evaluation may lead to a selection of more than one aspect of the possible alternative representations that are eventually taken up for a synthesis into final design. The next stage would involve incorporating syntactic features that would make these drawings into a graphical representation appropriate for use as a part of signage for public facilities.