OST_VMD_RETURN_NO_TYPE, the default, does not return the type as part of each converted element but just the data. All of the rest return the type and data as the two-element tuple. If BOOST_VMD_RETURN_TYPE is specified the specific type of the element is returned in the tuple. If BOOST_VMD_RETURN_TYPE_ARRAY is specified an array type is returned if the element is an array, else a tuple type is returned if the element is a tuple, else the actual type is returned for non-tuple data. If BOOST_VMD_RETURN_TYPE_