Does anyone know the VDI etching standard?

VDI is a spark pattern standard, as well as etching patterns and bite patterns. The etching patterns and bite patterns should be the same. VDI used to be the German standard VDI 3400, but now it is almost the European standard. It is different from the etching pattern. The spark pattern is relatively less uniform and the texture is different. Now all newly purchased spark machines are equipped with the VDI 3400. The pattern is the Chamille spark pattern. What kind of pattern needs to be achieved depends on the corresponding current and other parameters. The advantage is that the cost is much lower than that of etching, but of course the effect is also worse. The standard for etching patterns is generally based on Mold-Tech, and there is also the standard for Nihong's engraving.