The file woodmaps.inc contains color_maps designed for use in wood textures. The M_WoodXA maps are intended to be used in the first layer of a multilayer texture, but can be used in single-layer textures. The M_WoodXB maps contain transparent areas, and are intended to be used in upper texture layers.
M_Wood1A, ..., M_Wood19A
M_Wood1B, ..., M_Wood19B