Word 2007 - adding custom information invisible to the user in word elements

Question

Hi,

I would like to store some custom data on Word elements. In PowerPoint, every shape has a 'Tags' property, which is visible to programmers only, and anything can be stored in it.

It's described here: http://blogs.msdn.com/b/andrew_may/archive/2004/12/07/277696.aspx

Is there a convenient way to do it in Word?

Regards.