CreateSandInArea(<-area <-sandDef)
Creates sand of sandDef type in the area. Area is a V4 that specifies the lower left and upper right coordinates of a region.
CreateSandInArea(V4(0 0 256 256) 1) #Fills the bottom-left quarter of the map with stone CreateSandInArea(V4(0 0 512 512) 255) #Deletes all sand in the entire map