1<documentation title="PHP Constants">
2    <standard>
3    <![CDATA[
4    The <em>true</em>, <em>false</em> and <em>null</em> constants must always be uppercase.
5    ]]>
6    </standard>
7    <code_comparison>
8        <code title="Valid: uppercase constants">
9        <![CDATA[
10if ($var === <em>FALSE</em> || $var === <em>NULL</em>) {
11    $var = <em>TRUE</em>;
12}
13        ]]>
14        </code>
15        <code title="Invalid: lowercase constants">
16        <![CDATA[
17if ($var === <em>false</em> || $var === <em>null</em>) {
18    $var = <em>true</em>;
19}
20        ]]>
21        </code>
22    </code_comparison>
23</documentation>
24