Nested Lists in XHTML

Putting lists inside lists does not validate with the W3C Markup Validation Service. The only method to nest lists relatively with valid XHTML is to nest the entire list within a list element.

Example:

1
2
3
4
5
6
7
8

<ol>
	<li>List One</li>
	<li>List Two</li>
	<li>
		<ul><li>Sub-list One</li></ul>
	</li>
	<li>List Three</li>
</ol>

The following does NOT validate:

1
2
3
4
5
6

<ol>
	<li>List One</li>
	<li>List Two</li>
	<ul><li>Sub-list One</li></ul>
	<li>List Three</li>
</ol>

Trying to validate it produces the error “document type does not allow element “ul” here; assuming missing “li” start-tag.”. Although nesting it correctly, like in the first code example, it’s very difficult to style or make attractive and orderly.