In the City of Masks, a mask represents a Character, and the terms can be interchangeable. It is also, of course, the physical mask which by law and custom each person must wear. A specific mask is often associated with a costume.
The mask contains symbolic reference to the characteristics of the character portrayed. These symbolic correspondences are not a fully consistent or mechanical system that can be simply “read”; one must be familiar with the Book of Masks and with the masks currently in use in order to know the significance and map the mask onto the character and that character’s qualities (rather like medieval heraldry, only much more complicated).
People who are themselves living Characters can wear masks or half-masks portraying their own features with the insignia of their Character. The significance of the shape of these is:
The Commissioners of Masks wear masks made up of small masks.