Fuel System ?'s from a Newb...

Hello all,
I did my best to search the forums, read the FAQs, and read the help files. Stil couldn't find what I was looking for so I'm hoping you can help the new guy out...

Looking to do a basic tune on my 2000 GMC Sonoma (S-10) 4.3. Was starting with the easy stuff such as top sped limits, speedo calibrations for my larger tires, and so forth. Got to the fuel system tab and noticed that the fuel capacity listed in there is not what my tank holds (HPT shows 21.1 and actual tank is around 17). Did some reading in the forums and found that some of the F-body guys are recalibrating so that the gage actualy reads what's in the tank (novel idea there). So I figured I'd try this. Trouble is, I have 3 tables available and I'm not sure which one does what. They all refer to the "level". Is that the actual level of fuel in the tank? :shrug: The Gage output appears to be a measurement of PWM but I'm not sure how that relates to the other tables? Really just confused and needing a jump start here. :confused:

Any remedial help you can give on the following tables and what they do...
Gage output vs level
Primary volume vs level
Gage volume vs level

I also included a snap shot for you to view.

Once I have this figured out, I can gather some data when I fill up to check the calibrations.

Thanks ahead of time for any help.
Scott

Wow, that's pretty cool you can program your fuel gauge, lol.