Remove the padding on the inside and you will find a M2005 or similar certification sticker in there. My HJC helmet has the same sticker on the outside (says *** and SNELL Approved) but no rating. On the inside, if I remove the padding I find "M2005 Snell Approved Certified" or something like that stuck to the foam liner.
I had a similar experience when I was racing karts. The tech inspector tried to fail me because my helmet did not have a snell sticker on the back. We argued for awhile and finally he let me race under the condition that the track was not responsible for any head injury. Later that night I got home still mad about the inspection and started digging around in the helmet, where I found the SNELL M95 tag under the padding. Then I got really mad at the tech inspector for not knowing to look there
Anyway it's a good question, make sure you research it before you get in line for the inspection.