DomDocument::$preserveWhitespace and ::saveHtml()

00-test.php

$doc = new DomDocument;
$doc->preserveWhitespace = true;
$doc->formatOutput = false;

$doc->loadHtml(
'<ul id="ProjectSubmenu">
    <li><a href="/projects/markdown/" title="Markdown Project Page">Main</a></li>
    <li>
        <a href="/projects/markdown/basics" title="Markdown Basics">Basics</a>
    </li>
    <li><a class="selected" title="Markdown Syntax Documentation">Syntax</a></li>
    <li><a href="/projects/markdown/license" title="Pricing and License Information">License</a></li>
    <li><a href="/projects/markdown/dingus" title="Online Markdown Web Form">Dingus</a></li>
</ul>'
);

$listNode = $doc->getElementsByTagName('ul')->item(0);

echo $doc->saveHtml($listNode);

01-output.txt

<ul id="ProjectSubmenu">
<li><a href="/projects/markdown/" title="Markdown Project Page">Main</a></li>
    <li>
        <a href="/projects/markdown/basics" title="Markdown Basics">Basics</a>
    </li>
    <li><a class="selected" title="Markdown Syntax Documentation">Syntax</a></li>
    <li><a href="/projects/markdown/license" title="Pricing and License Information">License</a></li>
    <li><a href="/projects/markdown/dingus" title="Online Markdown Web Form">Dingus</a></li>
</ul>