2>

<p>The <code>boost::low_bits_mask_t</code> class template provides
constants for bit masks representing the lowest bits of a certain
amount.  The masks are equivalent to the value
(2<sup><code>Bits</code></sup> - 1), where <code>Bits</code> is the
template parameter.  The bit amount must be a nonnegative number from
zero to <i>Max</i>, where <dfn>Max</dfn> is the number of bits supported
by the largest unsigned built-in integral type.  The following table
describes the members of an instantiation of
<co