Fixed explanation of field options

Author: peterrehm

reference/forms/types/options/empty_data.rst.inc

@@ -8,10 +8,10 @@ choice is selected.
 
 The true default value of this option depends on the field options:
 
-* If ``required`` is ``true`` and ``data_class`` is set, then ``new $data_class()``;
-* If ``required`` is ``true`` and no ``data_class`` is set, then ``array()``;
-* If ``required`` is ``false``, then ``null``.
-
+* If ``data_class`` is set and  ``required`` is  ``true``, then ``null``;
+* If ``data_class`` is set and  ``required`` is  ``false``, then ``new $data_class()``;
+* If ``data_class`` is not set and  ``compound`` is  ``true``, then ``array()``;
+* If ``data_class`` is not set and  ``compound`` is  ``false``, then ``null``.
 
 But you can customize this to your needs. For example, if you want the ``gender`` field to be
 explicitly set to ``null`` when no value is selected, you can do it like this: