There’s a great explanation from Eventide’s Dan Gillespie found in this ancient thread:

https://www.eventideaudio.com/forums/topic/can-we-get-a-frequency-shifter/

And more toys to play here:

https://www.eventideaudio.com/forums/topic/xfade-away-24-preset-list/

Like you, I stumbled into this backwards, and found a whole new world to explore.