[Yaesu] FT-817 selector knob menu?

[Clark Savage Turner]

Anyone out there with the 817 notice that you can "push" the selector 
knob in (momentary) and a number (for me, its "007") comes up to the 
left of the frequency in the normal display?

On brief scan of the manual, I do not see what this is about.  Anyone 
can point me to info about it?  (I have no desire to fiddle with special 
menus, I just want to know what it is...  I had pushed it by accident 
while mobile/QRP and it was a bit disconcerting!)

73

Clark
WA3JPG