Underline Markup

Hello there I want to underline some text in a \markup command. Any search in the manual or Internet is matchless. Can anybody tell me how to do it? Shouldn't there be an option for underlining in the font-interface? Thank you Tiago Morin __

3 voice polyphony bug

{<<{\stemDown c'2.}\\{\stemDown s4 2}>>}>> } \score { \time 3/4 << {\stemUp f''2 e''4}\\ {\stemDown c'2.}\\ {\stemDown s4 2}>> } Another thing: In guitar it is comon to make an arpeggio down and up over the same