It associates a setup code and command with a device and key. It can go across devices or within a device. In my example, it takes the setup code from the AUD device and takes the command from the Vol+ key within that setup code and associates those with the Vol+ key within the CD device.

I didn't know you meant the UK version. It works the same, but I think the special key for defining things is labeled "Magic" on the UK version and "P" on the US version.

Many features of these remotes are the same across most models and are badly documented or completely undocumented for each model. The best available documentation is in Rob's improved version of the 15-1994 manual at
[Link: hifi-remote.com]