newmtl default
Ka 0 0 0
Kd 0 0 0
Ks 0 0 0
Kt 0.1 0.2 0.3
map_Kd -o 0.1 diffuse.jpg
map_Ks -o 0.1 0.2 specular.jpg
map_Ns -o 0.1 0.2 0.3 specular_highlight.jpg
map_bump -bm 3 bumpmap.jpg

newmtl bm2
Ka 0 0 0
Kd 0 0 0
Ks 0 0 0
Kt 0.1 0.2 0.3
# blendu
map_Kd -blendu on diffuse.jpg
map_Ks -blendv off specular.jpg
# -bm after filename
map_bump bumpmap2.jpg -bm 1.5