This is true, this will tell you most everything that your car was at least ordered with, and built with as far as options etc...
Go to John's site and on this page http://firstgenfirebird.org/registry/Documents.mv?Broadcast (or you go into the regestery form, then in the first line of instructions click on the "Body Broadcast sheet" and this will take you to an on-line version of a Broadcast sheet with all the boxes blank.) Enter the number or letter on your sheet to the same number bos, then you click on the "?" tab below each box to see the options that match what is filled in on your coupy, and will get a breakdown of all the option codes you have!
And make sure if you have anything that is not on the list that you contact John so he can add this documented information!