Multiple BGs

 "chapters"
{
	1	"background one filename"
	2	"background two filename"
}
"BackgroundMaps"
{
	1	"background one filename"
	2	"background two filename"
}

****

EX. - this is mine for TF2.

"chapters"
{
	1	"background_2fort_effects"
	2	"background_gravelpit_effects"
	3	"background_upward_effects"

}
"BackgroundMaps"
{
	1	"background_2fort_effects"
	2	"background_gravelpit_effects"
	3	"background_upward_effects"
}