Changes in HTML 5 - <ol> Tag

What's new in HTML 5

The start attribute, which was removed from HTML 4 and XHTML, has been resurrected in HTML 5. In addition, the reversed="reversed" boolean attribute has been added.

Differences between HTML 5 and earlier versions of HTML

The following attributes should not be coded on the <ol> tag because they either have been deprecated or were never officially supported:

The 2000-2010 Recommendations from the W3C HTML Working Group defined the HTML namespace for the ol element type name along with the names of all HTML element types. In older (pre-2000) versions of HTML, element type names were not associated with a namespace.