src/Doc/IsarRef/Document_Preparation.thy

   @{file "~~/lib/texinputs/pdfsetup.sty"}, which can be used via
   @{verbatim "\\usepackage{pdfsetup}"} in @{verbatim "root.tex"}, for
   example.
 
   The rail specification language is quoted here as Isabelle @{syntax
-  string}; it has its own grammar given below.
-
+  string} or text @{syntax "cartouche"}; it has its own grammar given
+  below.
+
+  \begingroup
+  \def\isasymnewline{\isatext{\tt\isacharbackslash<newline>}}
   @{rail \<open>
   rule? + ';'
   ;
   rule: ((identifier | @{syntax antiquotation}) ':')? body
   ;

   ;
   atom: '(' body? ')' | identifier |
     '@'? (string | @{syntax antiquotation}) |
     '\<newline>'
   \<close>}
+  \endgroup
 
   The lexical syntax of @{text "identifier"} coincides with that of
   @{syntax ident} in regular Isabelle syntax, but @{text string} uses
   single quotes instead of double quotes of the standard @{syntax
   string} category.