A first step in the process of designing these would be to identify the various aspects of a given public facility that need to be represented for communication purposes, by graphical symbols that will serve collectively as an interface for the user. The different aspects of this environment would usually include its facilities, its functional and organizational attributes, and certain informative and warning messages. For the sake of convenience we will refer to these various aspects as the 'message areas'. While considering their potentials for visualization into visual representations, the possible representations emerging under these various areas may be classified (refer Fig.1) using the Peircean Trichotomic Model of the semiotic process as:

a. Iconic
b. Indexical
c. Arbitrary (being referred here as arbitrary instead of as 'symbolic' in order to avoid a clash with the term graphic symbols).