Manual
3.4. metal:fill-slot
This attribute occurs only under metal:use-macro context.
This explicitly tells PHPTAL to replace a defined slot with the content provided under the metal:fill-slot attribute.
<span tal:condition="logged" metal:fill-slot="news_place"> <h2>user menu</h2> <ul> <li><a href="/user/action/inbox">inbox</a></li> <li><a href="/user/action/new">new mail</a></li> <li><a href="/user/action/disconnect">disconnect</a></li> </ul> </span>
Slots give the opportunity to define really customizable and reusable page templates with a simple push technology.