Roman Numeral rehearsal marks?

[N. Andrew Walsh]

Hi List,

is there any other available format for rehearsal marks? My client wants Roman numerals, and the workaround I've been using:

<>^\markup { \raise #4 \right-align \abs-fontsize #16 \bold { "IV" } }

doesn't work if the voice containing it is resting at that point (or, conversely, I don't know how to ensure that the \markup is always placed on the topmost stave of a system and no others). 

Is there a better way to do this? MWE:

\version "2.19.80"

\relative c'' {

  

  a1

  

  | %2

  <>^\markup { \right-align \abs-fontsize #16 \bold { "IV" } }

  a

  

  | %3

  b

  

}

Cheers,

A