Question

We’re getting some suspicious HTML from our designer. Is the following valid? (note the UL inside the UL)

<ul>
    <li>1</li>
    <ul>    
        <li>1.1</li>
        <li>1.2</li>
        <li>1.3</li>
    </ul>
    <li>2</li>
    <ul>    
        <li>1.1</li>
        <li>1.2</li>
        <li>1.3</li>
    </ul>
</ul>

Answer 1

According to the HTML 4 specs, the XHTML 2 specs and the HTML 5 specs that code is invalid.

HTML 4

<!ELEMENT UL – – (LI)+

This means that inside a <ul> there can only be multiple <li> elements.

XHTML

Both types of lists (ul|ol) are made up of sequences of list items defined by the li element.

HTML 5

Content model:
Zero or more li and script-supporting elements.

Note that script-supporting elements are elements that are not rendered, and currently include only <script> and <template>.