    practice be any numeric Python type. ``decimal.Decimal`` values retrieved
    from the database are now converted to ``float`` to make it easier to combine
    them with values used by the GIS libraries.
  
  ``select_related()`` prohibits non-relational fields for nested relations
  -------------------------------------------------------------------------
  
  Django 1.8 added validation for non-relational fields in ``select_related()``::
 
</s>
* In order to enable temporal subtraction you must set the
  ``supports_temporal_subtraction`` database feature flag to ``True`` and
  implement the ``DatabaseOperations.subtract_temporals()`` method. This
  method should return the SQL and parameters required to compute the
  difference in microseconds between the ``lhs`` and ``rhs`` arguments in the
  datatype used to store :class:`~django.db.models.DurationField`.

    practice be any numeric Python type. ``decimal.Decimal`` values retrieved
    from the database are now converted to ``float`` to make it easier to combine
    them with values used by the GIS libraries.
  
* In order to enable temporal subtraction you must set the
  ``supports_temporal_subtraction`` database feature flag to ``True`` and
  implement the ``DatabaseOperations.subtract_temporals()`` method. This
  method should return the SQL and parameters required to compute the
  difference in microseconds between the ``lhs`` and ``rhs`` arguments in the
  datatype used to store :class:`~django.db.models.DurationField`.

  ``select_related()`` prohibits non-relational fields for nested relations
  -------------------------------------------------------------------------
  
  Django 1.8 added validation for non-relational fields in ``select_related()``::
keep keep keep add keep keep keep keep
 Fixed #24793 -- Unified temporal difference support.
docs/releases/1.10.txt