The most clear example is on the main page, boost/libs/type_traits/index.html, about half way down starting with the section, "Transformations Between Types." Pretty much everything there that summarizes the features has the leading '::' in the "Expression" examples.
Oh, shucks, missed those.
Maybe the intent is simply to say that they are in ::boost, but I do not recall seeing this kind of specification in other boost docs, and mized with the coding standards it confused me (but obviously that is not a difficult task).
Even so, it's easy to be tripped up by this, and with luck I'm going to rewrite the type traits docs "real soon now", so I'll try and make this clearer.
Cool. BTW, how would you state the differences between using type_traits and mpl, as Dave suggested in this thread?
They're not really in competition, think of mpl as a good way to combine and use type traits to do interesting things. John.