[sdiy] undertstanding switches/muxes in a multi mode/preset setup

[Dan Snazelle]

hey there
 
can anyone help me understand what is going on in the switching section of this schematic?
 
http://www.freeinfosociety.com/media.php?id=675
 
i know how a 4052 works and i can see that there are multiple filters, but something about how the wires are drawn, i am confused as to how the switch is changing modes.
 
i see the pullup resistors, but it looks like the A and B are Always connected to ground through a cap.
 
any help would be greatly appreciated.
 
and actually, if anyone could recommend any other synth circuits that use switches/muxes,etc to allow you to page through settings with a switch or a momentary button, i would be very happy to see other applications
 
thanks!