HCE Filter, Green #1 = #11?

[craigclu]

I couldn't find definitive information on this... Is this brand of filter decent? I have one in 67mm, it's not marked MC so I assume it's not multi-coated? It's marked #1 but seems like a normal 11, are they the same?

[John Koehrer]

Maybe.
It's possible that HCE has decided to flout convention & provide their own values. Or perhaps there is no real standard. B&W and Nikon also do this.
I guess it's just to make life more interesting.