Here goes:
M...Mesial...toward the front of the mouth
D...Distal...toward the back of the mouth
O...Occlusal...biting Surface of theback teeth
F...Facial...toward the face..front teeth only
L..Lingual..toward the tongue
B..buccal...toward the cheek...back teeth only
I...Incisal...the tips of the front teeth....like Occlusal but for the front teeth
So a filling with the desiqnation of MODBL would have all of the surfaces of a back tooth filled. Hope this helps!!!