I know this is a rudimentary question but, I just can't seem to figure it out.  These parameters seem to be attached (i.e. not independent of/ to) each other.  Being new to all this I'm a bit befuddled.

Thanks in advance for any/all replies!

FRO is Feed Rate Override
and F is Feed
Hope that is a help

Thanks Brian for the reply.  I was beginning to think that it was too stupid of a question for anyone to bother with a reply.

Maybe I should have been a bit more specific in my question... let me try again.  Why would you want to "overide" the feed rate.  Can't you just put a new F command line in you G code to change feed rates within your program

Why do 2 different ways to control feed rate exist? 

Thanks,
Sid

You can change the FRO on the fly, during cutting. You set what you think is the appropriate speed in the Gcode, using F. But, if you need to speed up or slow down while cutting, you use the Feed Rate OVERRIDE.

Cool! Thanks!!