This standard BS EN 336:2013 Structural timber. Sizes, permitted deviations is classified in these ICS categories:
79.040 Wood, sawlogs and sawn timber
This European Standard specifies two classes of permitted deviations from target sizes for structural timber of softwood and hardwood species. It also specifies the moisture content to be used as a reference point for the measurement of sizes, and gives average values for changes in size due to changes in moisture content. It is applicable to sawn and prepared square-edged structural timber with parallel edges having sawn thicknesses or widths greater than 6 mm.