ers and can be returned as specific
      types either when invoking BOOST_VMD_GET_TYPE or when using return type modifiers.
      Furthermore VMD recognizes their individual v-types, BOOST_VMD_TYPE_NUMBER
      and BOOST_VMD_TYPE_TYPE, as VMD data when parsing sequences.
    </p>
<p>
      It is possible for the end-user to define his own identifier subtype. This
      is called a "user-defined subtype". Once a user-define subtype is
      created all the generic type facilities of VMD which subtypes such 