How to access the uniqueID property from an HtmlElement?

How can I access the uniqueID property from an HtmlElement?

I know how to cast from HtmlElement to MSHTML's inte开发者_Go百科rfaces, but I don't know which interface to use.

I figured it out:

mshtml.IHTMLUniqueName id = element.DomElement as mshtml.IHTMLUniqueName;
MessageBox.Show(id.uniqueID);