What is "rhgb" on the grub, kernel line?

[reg at dwf.com]

For Fedora2 (and 1?) grub starts Linux with an argument of
    
    rhgb quiet

Where are these kernel arguments described, and what do they do?

Ive scanned the kernel sources for the "rhgb" string and dont
find it.


-- 
                                        Reg.Clemens
                                        reg at dwf.com