## 3 Results and Discussion
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameters Combination 1** & **Parameters Combination 2** & **Spificance of an Increase in n, When v\({}_{\rm{f}}\) (f\({}_{\rm{z}}\))** \\ (**v\({}_{\rm{c}}\)/f\({}_{\rm{z}}\)**) & (**v\({}_{\rm{c}}\)/f\({}_{\rm{z}}\)**)** & **\(p\)-Value** & **Spificance of an Increase in n, When v\({}_{\rm{f}}\) (f\({}_{\rm{z}}\))** \\ \hline n\({}_{1}\)\(-\)v\({}_{\rm{f1}}\)\(-\)D\({}_{1}\) & n\({}_{2}\)\(-\)v\({}_{\rm{f1}}\)\(-\)D\({}_{1}\) & 0.03 & Increase of n significant for v\({}_{\rm{f1}}\) \\
28.39/0.49 & 56.59/0.25 & & \\ \hline n\({}_{1}\)\(-\)v\({}_{\rm{f1}}\)\(-\)D\({}_{2}\) & n\({}_{2}\)\(-\)v\({}_{\rm{f1}}\)\(-\)D\({}_{2}\) & 0.05 & Increase of n significant for v\({}_{\rm{f1}}\) \\
29.43/0.49 & 58.66/0.25 & & \\ \hline n\({}_{1}\)\(-\)v\({}_{\rm{f1}}\)\(-\)D\({}_{3}\) & n\({}_{2}\)\(-\)v\({}_{\rm{f1}}\)\(-\)D\({}_{3}\) & 0.752 & Increase of n not significant for v\({}_{\rm{f1}}\) \\
30.82/0.49 & 61.43/0.25 & & \\ \hline n\({}_{1}\)\(-\)v\({}_{\rm{f1}}\)\(-\)D\({}_{4}\) & n\({}_{2}\)\(-\)v\({}_{\rm{f1}}\)\(-\)D\({}_{4}\) & 0.792 & Increase of n not significant for v\({}_{\rm{f1}}\) \\
29.78/0.49 & 59.35/0.25 & & \\ \hline n\({}_{1}\)\(-\)v\({}_{\rm{f2}}\)\(-\)D\({}_{1}\) & n\({}_{2}\)\(-\)v\({}_{\rm{f2}}\)\(-\)D\({}_{1}\) & 0.001 & Increase of n significant for v\({}_{\rm{f2}}\) \\
28.39/1.79 & 56.59/0.90 & & \\ \hline n\({}_{1}\)\(-\)v\({}_{\rm{f2}}\)\(-\)D\({}_{2}\) & n\({}_{2}\)\(-\)v\({}_{\rm{f2}}\)\(-\)D\({}_{2}\) & 0.559 & Increase of n not significant for v\({}_{\rm{f2}}\) \\
29.43/1.79 & 58.66/0.90 & & \\ \hline n\({}_{1}\)\(-\)v\({}_{\rm{f2}}\)\(-\)D\({}_{3}\) & n\({}_{2}\)\(-\)v\({}_{\rm{f2}}\)\(-\)D\({}_{3}\) & 0.598 & Increase of n not significant for v\({}_{\rm{f2}}\) \\
30.82/1.79 & 61.43/0.90 & & \\ \hline n\({}_{1}\)\(-\)v\({}_{\rm{f2}}\)\(-\)D\({}_{4}\) & n\({}_{2}\)\(-\)v\({}_{\rm{f2}}\)\(-\)D\({}_{4}\) & 0.934 & Increase of n not significant for v\({}_{\rm{f2}}\) \\
29.78/1.79 & 59.35/0.90 & & \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Pairwise comparison of parameters combinations (vc/fz) for Rk and the level of significance for an increase in n (and local v\({}_{\rm{c}}\), respectively). Wood is a stratified heterogeneous material and apart from outliers located above the core roughness it also has outliers located below the core roughness. They can be seen as surface gaps, exemplified by yellow ellipses in Figure 8. Their origin can be deep anatomical cavities going below the marks caused by the cutting tool, but can also include accidental surface gaps when wood material is detached leaving unwanted voids in the material. Both of them will depend on the type and proportion of anatomical cells encountered by the cutting plane. The weakest zones should be those from the earlywood and those coinciding with the wood rays (radial surfaces). The processed samples did not consider a certain top wood surface orientation, which varied from radial to tangential and combinations like semi-radial and semi-tangential. For the above-mentioned reasons, the parameter Rv, which measures the deepest valley in the profile, had a high standard deviation (Table 4) in comparison with the core roughness Rk, depending on the local wood anatomy. Furthermore, Rv had values in the range of earlywood pores cavities reported for beech (8-45-85 \(\upmu\)m) [33] (p. 107) with the majority of them around the mean values given in the literature (45 \(\upmu\)m), while some of the deepest valleys were below 70 \(\upmu\)m. These observations can lead to the assumption that the isolated deep valleys seen in the roughness profiles, in most cases, belong to inherent wood anatomical cavities and are not processing defects.