I developed a new set of tactile / visual symbols for doors, for this project. Each symbol clearly indicates a door's type or status: open to the public, fire exit, alarmed, limited access and closed to the public. These symbols have been used on other projects as well and it is my hope that through usage they become a de facto standard. They are free for others to use, on a commercial basis, although I do retain the right to identify myself as the inventor.