Standard forms of upper and lower frame materials and left and right frame materials for door frames
Box frame
Upper frame material and left and right frame materials, B-grade and no grade
Upper frame material and left and right frame material grade A
Lower frame material B level and no level
A-grade lower frame material
S-shaped frame
B-grade and unclassified left and right frame materials
Upper frame material B grade and no grade
Lower frame material B level and no level