    These traits are all <span class="emphasis"><em>value traits</em></span>, which is to say the
        traits classes all inherit from <a class="link" href="../reference/integral_constant.html" title="integral_constant">integral_constant</a>,
        and are used to access some numerical property of a type. Often this is a
        simple true or false Boolean value, but in a few cases may be some other
        integer value (for example when dealing with type alignments, or array bounds:
        see <cod