Fermata on final double bar

[Jonathan Henkelman]

I am trying to typeset a piece of music that has a fermata above and below the 
final double barline.  I have come across the \mark command in the manual, but 
am having difficulty getting it to work when there are no notes after it.  
Does anyone have any hints on how to typeset this?  Does anyone have any idea 
what this means musically, i.e. maybe I'll just typeset the fermata over the 
final note!

Thanks in advance
Jonathan