field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">User agent string or NULL if not set</p>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>$xss_clean</strong> (<em>bool</em>) – Whether to apply XSS filtering</li>
</ul>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><