When you click an ASSIGN button anywhere on the ODC 2800 front panel, you will be presented with the Modulation Source Menu, a pop-up menu that looks like this:
The Modulation Source Menu lets you choose from the following sources:
Positive or negative output from ADSR 1 or ADSR 2
Sine, Triangle, Square, Sawtooth, or Ramp (rising sawtooth) from either of the two LFOs
Sawtooth, Pulse, or Sine outputs from any of the three VCOs
Violet, White, Pink, Brown, or Red Noise
The S/H Mixer, Sample / Hold Output, or Pitch Bend
Positive or negative output from the Modulation Wheel or Keyboard CV
Many of the sources on the popup menu have submenus that pop up for more choices. Some of these will offer more options than are normally available on the front panel, including sine wave outputs from the VCOs and a Red noise option.
The Modulation Menu is the same for every Assign button on ODC 2800, with one exception: the Aftertouch Controls, whose destination choices are outlined in that section.
Note that whenever a modulation routing is assigned in this way, the ASSIGN label underneath the button will be replaced with a label showing the selected source or destination, so you don't have to pop open the menu to see what you've assigned.