CNCPro Max Vel and Fast Jog

Hi everyone! Does anyone know what the difference btw the "fast jog"
and "max velocity" feature is in cncpro? I have noted that fast-jog
cannot be higher than max-velocity but fast-jog can be lower then
max-velocity. If you increase the max-vel it does not automatically
change the fast-jog to that same number..you have to manuelly go and
do it. However, if you decrease max-vel then fast-jog also goes to
that new number. Overall, the machines moves whatever the fast-jog
number is set to (this is what I have noticed). I don't see why there
is a max-velociy feature. any help?? Thanks again! You guys are GrEaT!
tauseef