\def\mmref#1#2{%
  \ifpdf%
    {\leavevmode%
     \startlink attr{/Border [0 0 0]}%
     goto file{maxima.pdf} name{#1}%
    }%
    \setcolor{\linkcolor}%
  \fi%
  #2%
  \ifpdf%
    \endlink%
  \fi%
}
