SID decoding

I have a 1992 cadillac deville purchased recently, and was just for kicks, running through some of the codes on the service identification tag and found a rather lengthy list of codes on one site but what puzzles me is that as comprehensive as that site's list was, there were 2 or 3 codes just on the 1st two lines that weren't in the list, and one of the codes, an IQ4, heck that list had NO i codes listed.

is there a complete list of codes for this model year so i can get all the information on the car?