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+``mathtext`` now supports ``\substack``
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+``\substack`` can be used to create multi-line subscripts or superscripts within an equation.
+
+To use it to enclose the math in a substack command as shown:
+
+.. code-block::
+
+    r'$\sum_{\substack{1\leq i\leq 3\\ 1\leq j\leq 5}}$'
+
+.. mathmpl::
+
+    \sum_{\substack{1\leq i\leq 3\\ 1\leq j\leq 5}}
+
+
+``mathtext`` now supports ``\middle`` delimiter
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The ``\middle`` delimiter has been added, and can now be used with the
+``\left`` and ``\right`` delimiters:
+
+To use the middle command enclose it in between the ``\left`` and
+``\right`` delimiter command as shown:
+
+.. code-block::
+
+    r'$\left( \frac{a}{b} \middle| q \right)$'
+
+.. mathmpl::
+
+    \left( \frac{a}{b} \middle| q \right)