File: vendor/squizlabs/php_codesniffer/src/Standards/Squiz/Docs/WhiteSpace/LanguageConstructSpacingStandard.xml

<documentation title="Language Construct Whitespace">
    <standard>
    <![CDATA[
    The PHP constructs echo, print, return, include, include_once, require, require_once, and new should have one space after them.
    ]]>
    </standard>
    <code_comparison>
        <code title="Valid: echo statement with a single space after it.">
        <![CDATA[
echo<em> </em>"hi";
        ]]>
        </code>
        <code title="Invalid: echo statement with no space after it.">
        <![CDATA[
echo<em></em>"hi";
        ]]>
        </code>
    </code_comparison>
</documentation>