That's cool. Never knew about those codes.
Yeah, they are in the back of the manual. Took a bit to find them.
Most people don't even read manuals. I do, but not prior to (intent to) purchase. Doing so is dangerous.
So that's why I have had a rapid build up of Test Gear I read spec. sheets carefully first, then look for a manual and gloss over it to at least make sure there is a better chance of repair if needed, then do a search to see if it is good or bad in general then punch the evilbay button after limited self justification of NEED to the collection
There is no real consideration of budget or cost
I read the manuals to find more stuff to hunt down. At least for the HP gear, simply look at the opening pages of the 'maintenance' section of the manual, and you should find a list of 'recommended' or (sometimes, even better) 'required' equipment to be used for calibration, troubleshooting and repair of your newly acquired piece of kit. Determine what you may lack that is listed, and use this information to begin new evilBay quests for said missing instruments (each of which will ALSO have a service manual containing such a list, fodder for further searching, and so as the flea poem ends, "and so, ad infinitum").
(Or, if all that seems too much research, just get some old HP catalogs and start working your way through them, getting one of everything.)
-Pat