To find out more about registration, see the book's Web site. For readability, Scheme programs are typeset using a small number of fonts. Italic words refer to program names and variables. Sans Serif items are constants and built-in operations. Boldface words are Scheme keywords.
Definitions come in three varieties.
There are those terms that concern the principles of programming and computing. The book uses slanted words to emphasize such definitions. Finally, the book also defines classes of data.