Stamps are placed on the edges and back of each sheet of  plywood so it can be properly identified. Figure 6-7 shows typical back-stamps and edge-marks found on a standard sheet of plywood. It shows all information needed about the sheet, except its actual size.

Figure 6-8 shows the stamps found on the backs of structural and standard sheathing panels. They vary somewhat from the standard stamps.

Figure 6-8.-Structural and standard sheathing identification symbols.

The actual grade is NOT given, NOR is the species group. The index numbers 48/24 and 32/ 16 give the maximum spacing in inches of supports. The number to the left of the slash is the maximum O.C. (on-center) spacing of supports for roof decking. The number to the right of the slash is the maximum O.C. spacing of supports for subfloors. A number 0 on the right of the slash indicates that the panel should NOT be used for subflooring. No reference to the index number is needed when the panel is to be used for wall sheathing.

Detailed information on specific types and grades and their uses can be found in commercial standards for the manufacture of plywoods established by the U.S. Department of Commerce. General plywood characteristics and architectural information can be found in the following publications: National Lumber Manufacturing Association, or the Architectural Graphic Standards. The latter book can be found in your units technical library.