final \makeatother -- catcodes appear to be global;

--- a/lib/texinputs/railsetup.sty	Tue May 03 18:47:22 2011 +0200
+++ b/lib/texinputs/railsetup.sty	Tue May 03 20:58:42 2011 +0200
@@ -1195,7 +1195,7 @@
 
 % default setup for Isabelle
 \newenvironment{railoutput}%
-{\begin{list}{}{\rail@param}\def\rail@expand{\relax}\makeatletter}{\end{list}}
+{\begin{list}{}{\rail@param}\def\rail@expand{\relax}\makeatletter}{\makeatother\end{list}}
 
 \def\rail@termfont{\isabellestyle{tt}}
 \def\rail@nontfont{\isabellestyle{it}}