I. Quality - An even structure caused by the natural growth. Knars, sap-wood, irregularities or obvious differences in the colour of the wood are not allowed.

II. Quality - An even structure caused by the natural growth. Small knars (1-2mm) are allowed.

III. Quality - An even structure caused by the natural growth. Tight accrete dark knars (10-12mm) are allowed.

IV. Quality - An even structure caused by the natural growth. Colourings, tight accrete dark knars to 15-20mm and sap-wood to 20% are acceptable.