Jessica Theodor wrote most of these pages, with some help from Dave Lindberg in the introduction and history of the data model and any complimentary remarks are his. Thanks to Rob Guralnick for the help with frames and JavaScript. These sites were very useful in designing these pages:

Netscape Frames by Charlton Rose
Introduction to JavaScript, Part 6, Stefan Koch

5/1/96 Rob Guralnick and Jessica Theodor revised the model and added notation to the diagrams. 7/15/96