\def\ensuremath{\relax
  \let\mathshift=$
  \ifmmode
    \global\let\ensurenonmath\relax
  \else
    \global\let\ensurenonmath=\mathshift
    \mathshift\relax
  \fi\relax}

\def\oeatt#1{\hbox{\tt #1}}
\def\oeattribute#1{\hbox{\tt #1}}
\def\oeval#1{\hbox{\it #1\/}}
\def\oetype#1{\hbox{\it #1\/}}
\let\oeRoman\roman
\def\oeroman#1{\hbox{\rm #1}}
\def\oecategory#1{\hbox{\it #1\/}}


\def\oetag#1{%
  \hbox{\lower 3pt\vbox{\hrule%
                        \hbox{\vrule\kern 2pt%
                              \vbox{\kern 2pt\hbox{\sf #1}\kern 2pt}%
                              \kern 2pt\vrule}%
                        \hrule}\kern 0.2ex}}

\def\oetop{\hbox{$\mathchar"023E$}}
\def\oebottom{\hbox{$\bot$}}
\def\oepipe{\hbox{$\,|\,$}}
\def\oenode#1{\hbox{\bf #1\strut}}

\def\oeavm#1{%
  \mathsurround=0pt%
  \let\quad=~%
  \hbox{$%
    \mskip-\thinmuskip%
    \left\lbrack%
    \mskip -0.5\thinmuskip%
    \matrix{\noalign{\vglue 0.75ex}%
            \ifx\empty#1\empty\kern1pt\cr\else\ignorespaces#1\crcr\fi%
            \noalign{\vglue 0.75ex}}%
    \mskip -0.5\thinmuskip%
    \right\rbrack%
    \mskip -\thinmuskip$}}

\def\oetavm#1#2{%
  \hbox{$\hbox{\vphantom{\oeavm{#2}}}_{\oetype{#1}\strut}\oeavm{#2}$}}

\def\oeattval#1#2{%
  \oeatt{#1}\hfill&\oeval{#2}\hfill\cr}
\let\oeav\oeattval

\def\oedisjunction#1{%
  \mathsurround=0pt%
  \let\quad=~%
  \hbox{$%
    \mskip-\thinmuskip%
    \left\lbrace%
    \mskip -0.5\thinmuskip%
    \matrix{\noalign{\vglue 0.75ex}%
            \ifx\empty#1\empty\kern1pt\cr\else\ignorespaces#1\crcr\fi%
            \noalign{\vglue 0.75ex}}%
    \mskip -0.5\thinmuskip%
    \right\rbrace%
    \mskip -\thinmuskip$}}

\def\oesequence#1{\relax
  \mathsurround=0pt%
  \hbox{$%
    \left\langle%
      \hbox{\ignorespaces #1}%
    \right\rangle$}}

\def\oesequence#1{\relax
  \mathsurround=0pt%
  \hbox{$%
    \left\langle%
      \hbox{\ignorespaces #1}%
    \right\rangle$}}

\def\oewidth#1{%
  \setbox0={#1}%
  \wd0}