What product are you trying to use it with?  Often there is a section in the product manual that describes usage with the FBV foot switches.

The FBV (a lot of users have code-named it the "Longboard", but that was never the official name) was designed back in the days of the Vetta series amplifiers. We no longer manufacture these controllers; they're legacy units.

The behavior of our controllers always depends on the actual compatible FBV device's internal features. In other words, if you connected an FBV to say, a PODxt vs. a Vetta amp (which is really the device it was intended for full-switch correspond control) vs. a Spider Valve HD100... you'll discover that not all of the switches will control the same parameters from device to device.

There's no such thing as "Favorite Channel" or "Stomp 2 & Stomp 3" on a Spider III amplifier or a PODxt. But those parameters are components of the Vetta's firmware/OS.

That's why it's important to know which device you're connecting it to... as the answer depends on the internal features of *that* unit; not the FBV per se (as BigChas52 mentioned <--- +1).