EN 172:1995 Personal eye protection - Sunlight filters for industrial use 

This standard specifies the scale numbers, transmittances, and related requirements for sun glare filters designed for industrial use. Other requirements for these types of filters are specified in EN 166. Section criteria and information pertaining to the use of these filters are available in Annex A. This standard does not apply to filters that protect against radiation from artificial sources, such as those used in solaria, nor does it apply to ski goggles. To confirm: a separate standard is forthcoming for sunglasses and sun glare filters intended for general use.

The numbering table for filters and the reference for marking oculars and frames are available in EN 166.