The basic rule of thumb is in any situation where it could get wet.
This means that the plywood is sanded on both faces of the sheet to make sure that it has a consistant thickness.
All Products that are certified must be stamped on the back of the sheet showing that the product is NZS 2269 certified,
Copper, Chomuim and Arsenic, it is a waterborne preservative that will usually be green in colour and will give you a H3.2 Treatment standard.
LOSP stands for Light Organic Solvent Preservative. The biggest difference is that it is a solvent based dry process and is clear in colour. (not Green)
FSC stands for Forest Stewardship Council
PEFC stands for Program for the endorsement of Forest Ceritication
What they both mean is that you can reky on the product coming from a fully sustainable renewable resource.