Doc'd that admin site booleans are tri-state.
@@ -606,8 +606,8 @@ subclass::
and add that method's name to ``list_display``. (See below for more
on custom methods in ``list_display``.)
- * If the field is a ``BooleanField``, Django will display a pretty "on" or
- "off" icon instead of ``True`` or ``False``.
+ * If the field is a ``BooleanField``, Django will display a pretty "yes",
+ "no", or "unknown" icon instead of ``True``, ``False``, or ``None``.
* If the string given is a method of the model, ``ModelAdmin`` or a
callable, Django will HTML-escape the output by default. To escape
@@ -664,9 +664,9 @@ subclass::
birth_date_view.empty_value_display = 'unknown'
* If the string given is a method of the model, ``ModelAdmin`` or a
- callable that returns True or False Django will display a pretty
- "on" or "off" icon if you give the method a ``boolean`` attribute
- whose value is ``True``.
+ callable that returns ``True``, ``False``, or ``None``, Django will
+ display a pretty "yes", "no", or "unknown" icon if you give the method a
+ ``boolean`` attribute whose value is ``True``.
Here's a full example model::
