diff -r 7e51c9f3d5a0 -r a5f86aed785b doc-src/TutorialI/Misc/document/natsum.tex
--- a/doc-src/TutorialI/Misc/document/natsum.tex	Tue Aug 29 15:13:10 2000 +0200
+++ b/doc-src/TutorialI/Misc/document/natsum.tex	Tue Aug 29 15:43:29 2000 +0200
@@ -1,4 +1,5 @@
-\begin{isabelle}%
+%
+\begin{isabellebody}%
 %
 \begin{isamarkuptext}%
 \noindent
@@ -22,7 +23,7 @@
 \isacommand{lemma}\ {\isachardoublequote}sum\ n\ {\isacharplus}\ sum\ n\ {\isacharequal}\ n{\isacharasterisk}{\isacharparenleft}Suc\ n{\isacharparenright}{\isachardoublequote}\isanewline
 \isacommand{apply}{\isacharparenleft}induct{\isacharunderscore}tac\ n{\isacharparenright}\isanewline
 \isacommand{by}{\isacharparenleft}auto{\isacharparenright}\isanewline
-\end{isabelle}%
+\end{isabellebody}%
 %%% Local Variables:
 %%% mode: latex
 %%% TeX-master: "root"