diff -r e8f6d918fde9 -r d3d56e1d2ec1 doc-src/Ref/classical.tex
--- a/doc-src/Ref/classical.tex	Sun Jul 23 11:59:21 2000 +0200
+++ b/doc-src/Ref/classical.tex	Sun Jul 23 12:01:05 2000 +0200
@@ -681,7 +681,7 @@
 current claset by \emph{extra} introduction, elimination, or destruct rules.
 These provide additional hints for the basic non-automated proof methods of
 Isabelle/Isar \cite{isabelle-isar-ref}.  The corresponding Isar attributes are
-``$intro??$'', ``$elim??$'', and ``$dest??$''.  Note that these extra rules do
+``$intro?$'', ``$elim?$'', and ``$dest?$''.  Note that these extra rules do
 not have any effect on classic Isabelle tactics.