Display's background colour

[Shaun Jackman]

Is it possible to change the X server's background colour using a
command line option to the Xserver or perhaps using an Xresource? I'd
like to do the equivalent of `xsetroot -solid white' but as soon as
possible in the X server startup sequence, that is to say, before
xinitrc runs.

Is there a comprehensive list of resources the X server itself uses?

Please cc me in your reply. Thanks!
Shaun