OBD-II Code P0440

Does anyone have the Chevy specific list of the OBD-II codes? Especially as pertains to the 1998 Lumina? I'm most interested in code P0440. According to http://www.obdii.com/codes.html this is P0440 Evaporative Emission Control System Malfunction. However, that is a generic code list and does not take into account manufacturer specific changes to the code list.

Also, any suggested things to diagnose and repair said issue?

Some updated info. The car passed NJ Inspection:

NO.x = 65
HC = 6
CO% = 0.01
CO2% = 15.3
O2% = 0.1

Tank Pressure = N/A or Not Tested
Gas Cap = Passed
Purge = N/A or Not Tested
Tampering = Passed
Visible Smoke = Passed

A P0440 means you have a leak in your gas vapor system. Could be just a loose gas cap or a hole in the evap system lines.

A P0440 means you have a leak in your gas vapor system. Could be just a loose gas cap or a hole in the evap system lines.

I have a 1998 Lumina which is showing this code as well as of this morning. The car is running fine, but I'm just wondering if there is anything in particular we need to do to fix this? Is driving it like this going to damage anything in any way?

P0440 is "Evaporative Emission (EVAP) System " according to http://pcm.dxsoftware.com/dtcs.htm
I had this in a 2000 Century when the gas cap wa loose. It will eventually clear itseld but takes several days of driving to do so. I think the computer counts a certain number of engine start/stop cycles then clears the code. But if you have a code reader you can probably clear it right now.
Since the cap passed the test, but the tank pressure was not tested, you might listen for the hiss of pressure when you loosen the cap after driving. If you don't hear it, there might be a leak somewhere other than the cap. (hoses, lines, charcoal canister) maybe even where the fuel guage mounts on the tank, but you'd probably smell gas if it were there. Check the cap again carefully first, that is the easiest thing to do. Any torn or rough rubber seals?

I posted my question to two other forums and feel pretty comfortable that if there is in fact a leak it has to be pretty small. We do not have emissions testing here so I'm not concerned with passing that. The gas cap appears to be intact and on correctly. We cleared the code and I have been driving it for the last three days without the light coming back on. I just wanted to make sure I wasn't going to somehow cause damage to the engine by driving it with this code showing. Thanks again! I appreciate the input.