| Characteristic | Requirement of prEN13329 Ac3 | Requirement of GB 18102-2007 |
| Thickness of element,t | Δ taverage ≤0.5mm, on nominal value tmax-tmin ≤0.5mm | The same |
| Length of the surface layer,l | For the nominal values given, no measured value shall exceed: |≤1500: Δ|≤0.5mm |>1500mm: Δ|≤0.3mm/m | Δ|≤1.0mm , Δ|≤2.0mm |
| Width of the surface layer, w | Δ Waverage ≤0.1mm, on nominal value Wmax-Wmin ≤0.2mm | The same |
| Squared of the element, q | Δ | Δ Waverage ≤0.1mm, on nominal value | Wmax | Wmin ≤0.2mm, qmax ≤0.2mm | No requrement |
| Straightness of the surface layer, s | qmax ≤0.3mm/m | The same |
| Flatness of the element, f | Maximum single values: fw,concave ≤0.15% fw,convex ≤0.20% fi, concave ≤0.50% fi,convex ≤1.00% | The same |
| Openings between element, o | Oaverage ≤0.15mm , Omax ≤0.2mm | The same |
| Height difference between elements, h | haverage ≤0.1mm , hmax ≤0.15mm | The same |
| Dimensional variations after changes in relative humidity, δ l, δ w | δ laverage= δ waverage ≤0.9mm | No requirement |
