File: vendor/wp-coding-standards/wpcs/WordPress/Docs/Arrays/ArrayKeySpacingRestrictionsStandard.xml

<documentation title="Array Key Spacing Restrictions">
    <standard>
    <![CDATA[
      When referring to array items, only include a space around the index if it is a variable or the key is concatenated.
    ]]>
    </standard>
    <code_comparison>
        <code title="Valid: Correct spacing around the index keys">
        <![CDATA[
$post       = $posts<em>[ </em>$post_id<em> ]</em>;
$post_title = $post<em>[ </em>'concatenated' . $title<em> ]</em>;
$post       = $posts<em>[ </em>HOME_PAGE<em> ]</em>;
$post       = $posts<em>[</em>123<em>]</em>;
$post_title = $post<em>[</em>'post_title'<em>]</em>;
        ]]>
        </code>
        <code title="Invalid: Incorrect spacing around the index keys">
        <![CDATA[
$post       = $posts<em>[</em>$post_id<em>]</em>;
$post_title = $post<em>[</em>'concatenated' . $title<em> ]</em>;
$post       = $posts<em>[</em>HOME_PAGE<em>]</em>;
$post       = $posts<em>[ </em>123<em> ]</em>;
$post_title = $post<em>[ </em>'post_title'<em> ]</em>;
        ]]>
        </code>
    </code_comparison>
</documentation>