Changes in HTML 5 - <menu> Tag
What's new in HTML 5
The <menu> tag has been redefined in HTML version 5. In addition, the label, type and global contextmenu attributes have been added.
Differences between HTML 5 and earlier versions of HTML
The <menu> tag was deprecated in HTML version 4 and has now been redefined in HTML 5. Make sure that you are using the HTML 5 definition of the <menu> tag, not a pre-HTML v4 definition.
The 2000-2010 Recommendations from the W3C HTML Working Group defined the HTML namespace for the menu 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.