Fix a very minor (but annoying when looking for things!) markup nit.
diff --git a/Doc/ref/ref3.tex b/Doc/ref/ref3.tex
index a82ce8c..06155c0 100644
--- a/Doc/ref/ref3.tex
+++ b/Doc/ref/ref3.tex
@@ -1,5 +1,6 @@
\chapter{Data model\label{datamodel}}
+
\section{Objects, values and types\label{objects}}
\dfn{Objects} are Python's abstraction for data. All data in a Python
@@ -95,6 +96,7 @@
(Note that \samp{c = d = []} assigns the same object to both
\code{c} and \code{d}.)
+
\section{The standard type hierarchy\label{types}}
Below is a list of the types that are built into Python. Extension