DInput axis mapping explanation

[Michael Gardner]

Please forgive me if this is the wrong list or a stupid question, but I already tried wine-users and the WineHQ forums and no one could answer. I'm trying to understand Wine's DirectInput axis mapping feature (registry key HKEY_CURRENT_USER\Software\Wine\DirectInput). The documentation at http://wiki.winehq.org/UsefulRegistryKeys gives some details but seems to assume you already know how the feature works. (You could also consider this an RFE for better DInput axis mapping docs, which I'd be happy to write if I can first understand the feature.)

I understand that I can make a registry key with the same name as my joystick device and a value that's a comma-separated list of axes, which will act as some kind of mapping. But how does this mapping work? What is being mapped to what, exactly? The docs give an example mapping without explaining what it does, or how you'd arrive at that mapping given whatever result you're looking for.

I've also read https://forum.winehq.org/viewtopic.php?t=14899, but it also doesn't explain how these mappings work in the abstract.

Once again, my apologies if this is the wrong place, but if there's anyone who might have the knowledge I'm looking for then it would be the Wine devs.