t;OR&quot; keywords, which affect how
the expression is evaluated: if &quot;AND&quot; is used, then <b>all</b>
portions of the expression must evaluate to TRUE for the configuration context
to be applied to the current session; if &quot;OR&quot; is used, then <b>any</b>
portion of the expression must be TRUE for the context to be applied.  The
default setting for <code>&lt;IfClass&gt;</code> is &quot;OR&quot;.

<p>
If the &quot;regex&quot; keyword is used, the <em>regexp</em> should be a
regular expression 