diff -r 824d3f1d8de6 -r 2080fe35abea doc-src/IsarImplementation/Thy/document/Syntax.tex
--- a/doc-src/IsarImplementation/Thy/document/Syntax.tex	Tue May 03 20:59:24 2011 +0200
+++ b/doc-src/IsarImplementation/Thy/document/Syntax.tex	Tue May 03 21:07:24 2011 +0200
@@ -168,7 +168,7 @@
   \end{matharray}
 
   \begin{railoutput}
-\rail@begin{4}{\isa{}}
+\rail@begin{4}{}
 \rail@bar
 \rail@term{\hyperlink{ML antiquotation.class-syntax}{\mbox{\isa{class{\isaliteral{5F}{\isacharunderscore}}syntax}}}}[]
 \rail@nextbar{1}