CD Int plywoodCS45-55Natron Plywood?

Question:what does this mean?

Answers:
CD is the grade of the plywood. One side is "C", the other is "D". Both C and D allow for knot holes (A and B grades do not) with the number and size being more in D. CD plywood is used where appearance is not important.

The "Int" indicates the plywood is for interior use only. The glue will fail if the plywood is exposed to the elements.

CS45-55 refers to a government issued "Commercial Standard" that has not been commonly used for several years. I think CS45-55 was for douglas fir veneer, but not sure.

Natron is the manufacturer of the plywood.