Softwood & Hardwood —
Veneer logs (Highest Quality).
Factory Logs (Lumber Quality): The USDA FS usually divide them into 3 grades: F1, F2 and F3.
Low quality logs have two classes: construction wood (where appearance is not a concern) and local-use for use in pallets an in products where standards are not required. Straightness (i.e. presence of weeeps) and taper also affect grade.