Golly - gee, can somebody who actually owns and uses this exact filter for the past 5 years take a wild guess at what it is?
Okay, I lied, I actually have been using the 022, not the 023. Buy close enough for horseshoes and handgrenades, eh?
At the time I bought my 022, it was, supposedly according to the camera store sales guy, the deepest "yellow" they sold in B+W filters before you got into the orange range. In fact, I have 041 that was once described as "orange-red", and when I want something really dramatic, that's about as far as I go. Personally I only use the deep red when shooting infra-red. Anyhow, for making white clouds stand out against a blue sky without the sky going all dark on you, the 022 is pretty good for me. Past that, you start getting darker/blacker skies.
However, there is a bone of contention here as to yellow vs orange, as my 022 only says "medium yellow", not a deep yellow - but then isn't "deep yellow" really an orange or amber? To others around who saw the filters higher than 022 when I bought mine, everything came across as more of a light orange. Your milage may vary.
As for the "3X" not sure what to tell you. My 022 says "2X" as as far as exposure compensation goes, when using it, I have always shot my 400 film - be it T-Max, Tri-x, HP5, etc, etc, at 200 ASA, and never had a problem. For the 041 filter, the orange-red one, it says "4x" on it, so for it I meter at 100 ASA, and again, things seem to be bang on for me.
The "67E" is the filter size. I own a couple of of B+W filters in 67mm size, and all of them say "67E"
If already own a light yellow filter, well then try this one out - I think you will find there are times when it is useful, because realistically I find that even orange filters are too "dramatic" save for certian shots. For everyday use in landscapes, this one may be just right.
If you are feeling exceptionally silly some day, try out a B+W 091 deep, deep red filter. Outside of use for IR film, it makes almost any other emulsion, from tech pan to tri-x, come out looking almost like lithographic film. Develop in D-19, and you do have litho-film! Oh yeah, it has "8X" on it - hey, I didn't you always want to shoot 12.5 ASA film!
joe