diff -r 7e51c9f3d5a0 -r a5f86aed785b doc-src/TutorialI/Misc/document/Tree2.tex
--- a/doc-src/TutorialI/Misc/document/Tree2.tex	Tue Aug 29 15:13:10 2000 +0200
+++ b/doc-src/TutorialI/Misc/document/Tree2.tex	Tue Aug 29 15:43:29 2000 +0200
@@ -1,4 +1,5 @@
-\begin{isabelle}%
+%
+\begin{isabellebody}%
 %
 \begin{isamarkuptext}%
 \noindent In Exercise~\ref{ex:Tree} we defined a function
@@ -11,7 +12,7 @@
 \begin{isamarkuptext}%
 \noindent Define \isa{flatten2} and prove%
 \end{isamarkuptext}%
-\isacommand{lemma}\ {\isachardoublequote}flatten\isadigit{2}\ t\ {\isacharbrackleft}{\isacharbrackright}\ {\isacharequal}\ flatten\ t{\isachardoublequote}\end{isabelle}%
+\isacommand{lemma}\ {\isachardoublequote}flatten\isadigit{2}\ t\ {\isacharbrackleft}{\isacharbrackright}\ {\isacharequal}\ flatten\ t{\isachardoublequote}\end{isabellebody}%
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