\input showkeys.sty

\ifx\nullocplist\undefined
\RequirePackage{verbatim}
\def\@verb@year{\jobname.tmp}
\newwrite\verbatim@out

%% label swapping
\def\@lbibitem[#1]#2{\item[\@biblabel{#1}\hfill]\if@filesw
      {\let\protect\noexpand
       \immediate
       \write\@auxout{\string\bibcite{#2}%
        {#1\string\make@josa{#1}}}}\fi%
    \llap{\smash{\SK@labelcolor\fbox{%
                 \normalfont\small\ttfamily#2}\quad}}\ignorespaces}

\def\SK@@label#1>#2\SK@{%
  \toks@{#2}\edef\reserved@a{\the\toks@}%
  \edef\reserved@a{\expandafter\strip@prefix\meaning\reserved@a}%
  \immediate\openout\verbatim@out\@verb@year%
  \immediate\write\verbatim@out{\reserved@a}%
  \immediate\closeout\verbatim@out%
  \def\verbatim@processline{%
    {\setbox\@tempboxa=\hbox{\the\verbatim@line}%
      \hsize=\wd\@tempboxa
      \the\verbatim@line\par}}%
  \setbox\@tempboxa=\vbox{\parskip=0pt\topsep=0pt\partopsep=0pt
    \footnotesize\verbatiminput{\@verb@year}}%
  \gdef\SK@lab{\smash{\SK@labelcolor\fbox{%
                      \normalfont\small\box\@tempboxa}}}%
  \ifvmode
    \if@inlabel
      \global\setbox\@labels\hbox{%
        \llap{\SK@lab\SK@lab@relax
              \kern\@totalleftmargin\kern\marginparsep}%
        \box\@labels}%
    \else
      \dimen@\prevdepth
      \nointerlineskip
      \ifinner
        \skip@\lastskip\unskip
        \advance\skip@\lastskip\unskip
        \setbox\z@\lastbox
        \ifvoid\z@
          \llap{\SK@lab\SK@lab@relax\kern\marginparsep}%
        \else
          \hbox{\box\z@\kern\marginparsep\SK@labx}%
        \fi
        \vskip\skip@
      \else
        \llap{\SK@lab\SK@lab@relax\kern\marginparsep}%
      \fi
      \prevdepth\dimen@
    \fi
  \else
    \csname SK@\@currenvir\endcsname
    \ifSK@equation\else
      \ifmmode
        \SK@labx
      \else
        \ifinner
          \rlap\SK@lab
      \else
          \vadjust{\llap{\SK@lab\kern\marginparsep}}%
        \fi
        \SK@lab@relax
      \fi
    \fi
  \fi}

\def\SK@@ref#1>#2\SK@{%
  \toks@{#2}\edef\reserved@a{\the\toks@}%
  \edef\reserved@a{\expandafter\strip@prefix\meaning\reserved@a}%
  \immediate\openout\verbatim@out \@verb@year
  \immediate\write\verbatim@out{\reserved@a}%
  \immediate\closeout\verbatim@out
  \def\verbatim@processline{%
    {\setbox\@tempboxa=\hbox{\the\verbatim@line}%
      \hsize=\wd\@tempboxa
      \the\verbatim@line\par}}%
  \setbox\@tempboxa=\vbox{\parskip=0pt\topsep=0pt\partopsep=0pt
    \footnotesize\verbatiminput{\@verb@year}\hrule}%
  \leavevmode\vbox to\z@{%
    \vss
    \SK@refcolor
    \rlap{\vrule\raise .75em\hbox{\box\@tempboxa}}}}
\fi

\endinput

%% End of file `showhkeys.sty'.