Underlined key accelerators

Hello all,

I'm writing user interface documentation, which mentions GUI items which have 
key accelerators. For example, "Cancel" buttons often have the "C" 
underlined, and when "alt+C" is pressed, the button is activated.

How do I mark an underline in docbook? Note, this is not representation or 
formatting, but the actual content(AFAICT). 


Cheers,


			Frans