diff --git a/Documentation/card10-cfg.rst b/Documentation/card10-cfg.rst
index 3b3fdf7ab2f25229a314f96734b4cfe613c3abbf..8ad094c0e8c2a8de425990bb72c5eb8e05472698 100644
--- a/Documentation/card10-cfg.rst
+++ b/Documentation/card10-cfg.rst
@@ -40,4 +40,6 @@ Option name     Type       Description
 ``execute_elf`` Boolean    Allow running of binary :ref:`l0dables`. These files can be nefarious, so this option is off by default.
 --------------- ---------- -----------
 ``timezone``    String     Timezone for card10; must be of format ``[+-]HHMM``.  Examples: ``+0800``, ``-0200``
+--------------- ---------- -----------
+``default_app`` String     Full path to the exectutable file of the default application. If this option is not set,``apps/analog_clock/__init__.py`` is used.
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