There are 4 scripts that comprise Registry v.3.0. Here's just a quick run down on what each does. Click on the name to view the source code

reg-admin.pl: reg-admin.pl is the administrative program that allows you to edit your preferences and to delete unwanted entries

reg-config.pl This script doesn't really do anything but hold your user preferences

registry.pl This is the script that adds the new entry to the database

showentries.cgi This is what is referenced in the index.shtml page. This opens the database, and displays your entries.

The other files included with the Registry 3.0 distribution are:
id.txt     A text file that only holds a number (used to number each new entry)
reg-data.txt     The actual flat file database which holds each entry
index.shtml     This is the HTML file that displays your entries (calling showentries.cgi via an SSI command)
signreg.html     This is the HTML form for users to add a new entry