The various classes of clothing

I remember when clothing was classified by formal, business casual and casual. Now, it's out of control.

If you go to Rate Vegas and look at the attire that should be worn in the restaurants, you will find "Any Attire", "Resort Upscale" and "Jacket Required". This dovetails pretty well with the formal/buscas/cas clasification. But today, I just got a response from a restaurant that I made reservations at. In the confirmation, they stated that the dress code is "smart casual". I've been there previously, so I know what's acceptable and what's not, but still, what would you classify "smart casual" as?