Does the depth of sunglasses have industry standards?

Thank you. The depth of sunglasses, the industry is to light transmittance as indicators, such as: Ray-Ban's most classic green gray glass lenses, light transmittance of 15%, marked as: G15 lenses (G for green, 15 for 15% light transmittance). Sunglasses, I know, the minimum transmittance of 5% lenses, has been very deep, the highest transmittance of 45%, has been very shallow. Of course, for some time, popular use of transparent lenses, covered with a layer of progressive mercury, higher transmittance, about 70%. In the standard of the Ministry of light industry, it is necessary to clearly distinguish the visor or light lens on the tag. But this sort of classification doesn't make much sense to users. It is important to emphasize that the depth of the lens does not interfere with uv. We now match the optical lenses, as long as the regular factory produced lenses can block ultraviolet light. Looking at the sun with sunglasses depends on the amount of time it takes to see a total solar eclipse. Use a special Baden film lens.