What is BND? MIDI Pitch Bend?
MIDI Pitch Bend allows the pedal to receive controller change messages from the pitch wheel of a keyboard or synthesizer, for example.
Is C99 the condition “Active”?
I think you’ve misinterpreted what this part of the manual is saying. In short, when selecting an external control source you may either assign it to respond to an external pitch wheel (MIDI Pitch Bend) or you can assign any available function to its own CC number from 0 (zero) to 99. If you choose the latter, you will have to send a value along with the CC#. Depending on the function, you’ll either send it a value from 0-127 or if it’s an ON/OFF type command, 0 for OFF and 127 for on.
Sounds like this is related to what I’ve discussed above, but I recommend finding a good tutorial on your particular controller. While almost all MIDI controllers work alike, this would be a good question for the forums of that manufacturer. I know there are great Boss users groups on Facebook, for example.