======Core Optional Tag======

=====CORE:OPTIONAL=====

Show template content at runtime when a value in the runtime [[class:datasource|Data Source]] has been populated. For example:

====Syntax====
<code xml>

  <core:optional for="IsLoggedIn">
    <p><a href='logout.php'>log out</a></p>
  </core:optional>
  
  <core:default for="IsLoggedIn">
    <p><a href='login.php'>log in</a></p>
  </core:default>

</code>

====Description====

The ''for'' attribute is used to identify the name of the variable in the dataspace. 

This tag is often used in conjunction with the [[tag:core:default|<core:default>]] tag for simple if/else logic.

====Examples====

Please have a look at the [[http://wact.sourceforge.net/examples/show.php?group=tags/|examples]] section to see this tag in action.