[EricH]

Honestly, I would hope that an ASTM rating would be enough. If FIRST won't take ASTM because it isn't ANSI...

You would want to have papers or something--often it'll be marked on the lens. A package would be ideal, but often not available. A forum post probably wouldn't be enough--not enough authority/weight behind it; unless, of course, it came from a known manufacturer. A website spec sheet would probably work.

As an example, I have a pair of safety glasses marked with a bunch of numbers in various non-see-through places. Some of those may be model numbers; others could be standard numbers that it's tested to; I'm not exactly certain which is which.