diff -r 5965a0a60c85 -r 7efe226c50e4 lib/texinputs/isabelle.sty
--- a/lib/texinputs/isabelle.sty	Fri Apr 12 23:09:03 2019 +0200
+++ b/lib/texinputs/isabelle.sty	Sat Apr 13 12:45:38 2019 +0200
@@ -127,7 +127,6 @@
 \newcommand{\isakeywordcontrol}[1]
 {\emph{\normalfont\bfseries\itshape\def\isacharunderscore{\isacharunderscorekeyword}#1\,}}
 
-\newcommand{\isamarkupheader}[1]{\section{#1}}
 \newcommand{\isamarkupchapter}[1]{\chapter{#1}}
 \newcommand{\isamarkupsection}[1]{\section{#1}}
 \newcommand{\isamarkupsubsection}[1]{\subsection{#1}}