The following sentence in typeof.htm: Other integral types, such as enums, need to be described explicitly with the BOOST_TYPEOF_INTEGRAL macro, like (BOOST_TYPEOF_INTEGRAL(MyEnum)) contrudicts with footnote in 3.9.1/7: 43) Therefore, enumerations (7.2) are not integral: however, enumerations can be promoted to int, unsigned int, long or unsigned long, as specified in 4.5 It should be easy to fix documentation. Not sure what to do with BOOST_TYPEOF_INTEGRAL, though. BTW, it reminds me of mpl::integral_c and this item in MPL TODO list: * vector_c, range_c et al. don't work with enumeration types * http://thread.gmane.org/gmane.comp.lib.boost.devel/116955 * http://article.gmane.org/gmane.comp.lib.boost.devel/116940 * http://thread.gmane.org/gmane.comp.lib.boost.user/9219 -- Alexander Nasonov