Is There Documentation For The Audio Controls In XP ?

Is there documentation for the audio controls that are available
in Windows XP ?

(This is what I'm asking if there is written documentation for.)

When you quickly double-click on the volume' icon in the
Tray on the Desktop a window opens named 'Volume Control'
and (on my PC) it has a series of slider adjustments labeled
'Speaker Volume', 'Wave Volume', 'SW Synth Volume',
'CD Player Volume' and 'Input Monitor Volume.

Then if you use the pull-down available in 'Options' (on the
'Volume Control' window) you can select 'Properties' and then
select 'Recording' and the 'Volume Control' window changes
to 'Recording Control'. In the 'Recording Control' window you
can have (on my PC) slider adjustments for up to three inputs
('Stereo Mix Volume', 'Line In Volume' and 'Microphone
Volume').

Is there documentation that explains what all these adjustments
do ? Most of the controls are self-explanatory but I have never
understood why the 'Wave Volume' slider affects sound playback
level (as does the 'Volume Control Volume' slider) when listening
to a CD or a streaming Web soundcast.

(Background)
I have recently purchased a computer controlled shortwave
receiver (the Tentec RX-320D) and for the first time had a need
to connect an audio input to my PC. Up until then I had always
just had sound coming from the computer (playing a CD, listening
to streaming audio) but to connect up the SW receiver I had to
figure out how to control audio coming in to the PC. That was the
first time I found how to select the 'Recording Level' window and
select 'Line In'.

That experience got me to thinking about finding documentation
on the various audio selections and level adjustments.

Thanks;

Paul