From man(5) xorg.conf:
Various Option flags may be specified in the Screen section. Some are driver-specific and are described in the driver documentation. Others are driver-independent, and will eventually be described here.
Eventually doesn't help today. The option I am particularly interested in is the backing store. Since I can find no documentation, I can't determine the correct spelling, syntax or even the format of the option statement. I have tried several variations without success.
Is there any documentation anywhere?
If so, where?
If not, is there an initiate willing to risk the wrath of Xorg by sharing the secret incantations?