F10 Preview - single user mode, small glitch

[G.Wolfe Woodbury]

GRUB command line parameter "S1" used to bring on single user mode
(according to my reporter) but things have changed (probably in the
kernel) so that "single" is required to get things right.

Me, I always used "S" or "single" from the first introduction of LILO
and GRUB, so this is a little confused sounding to me.

Can someone explain the details of the "S", "1", "3", "5" and "single"
kernel parameters behaviour?

AIUI, they are passed to "init" to set the initial state of the system,
and "single" is a synonym for "S" and that "S" and "1" are equivalent.

TIA
-- 
Wolfe