There are several Microsoft Word documents here detailing data creation methods and with various dictionaries describing the included and derived variables.
The Database Creation Description is meant to walk a user through some of the steps detailed in the SAS code with this project.
The alphabetical list of variables is intended for users as sometimes this makes some coding steps easier to copy and paste from this list instead of retyping.
The NIS Data Dictionary contains some general dataset description as well as each variable's responses.