%    Instructions: Typeset this document using the format file that you
%    used for AMSLaTeX version 1.1 (or 1.0) documents. The message
%    printed on screen (i.e. in the TeX log, for Textures users) will
%    advise you whether you should add `newlfont' or `oldlfont' to the
%    documentstyle options list of existing AMSLaTeX documents, when
%    running them with LaTeX2e.
 
\documentstyle{article}
\begin{document}
\output{\setbox0\box255\relax}% don't create .dvi file

\it\bf \expandafter\let\expandafter\itbf\the\font
\bf\it \expandafter\let\expandafter\bfit\the\font
\newlinechar=`\!
\ifx\itbf\bfit
\typeout{!%
============================================================!%
New-style font switching detected.!%
!%
To process your existing AMSLaTeX documents with LaTeX2e,!%
you should add `newlfont' to the documentstyle options list.!%
============================================================!%
}%
\else
\typeout{!%
============================================================!%
Old-style font switching detected.!%
!%
To process your existing AMSLaTeX documents with LaTeX2e,!%
you should add `oldlfont' to the documentstyle options list.!%
============================================================!%
}%
\fi

\end{document}