">nullptr</span></code> during serialization, this value
          is ignored. Otherwise, it represents the number of valid body octets pointed
          to by <code class="computeroutput"><span class="identifier">data</span></code>.
        </p>
<h6>
<a name="beast.ref.boost__beast__http__buffer_body__value_type.size.h3"></a>
          <span class="phrase"><a name="beast.ref.boost__beast__http__buffer_body__value_type.size.when_parsing"></a></span><a class="link" href="size.html#beast.ref.boost__beast__htt