There are four parts:
1. Tiger-binary data (Landview-II datasets)
2. Tigerwww program in two sections:
   a. file reading routines
   b. cartographic routines that make the map and send it to STDOUT
3. Mapgen interface script (perl)
   takes URL http:/...../mapgen/options, and passes options to tigerwww
   this is how all interfaces would access the maps
4. Main WWW Map Browser Interface script (perl)
   builds html page, including
   <img src="http://..../mapbrowse/options">
   which call #3, treating it like an image.