[1.9.x] Fixed #26837 -- Documented ModelMultipleChoiceField.to_field_name

    Allows the selection of one or more model objects, suitable for

    representing a many-to-many relation. As with :class:`ModelChoiceField`,

    you can use ``label_from_instance`` to customize the object

    representations, and ``queryset`` is a required parameter:

    representations.

    A single argument is required:

    .. attribute:: queryset

        A ``QuerySet`` of model objects from which the choices for the

        field will be derived, and which will be used to validate the

        user's selection.

        Same as :class:`ModelChoiceField.queryset`.

    Takes one optional argument:

    .. attribute:: to_field_name

        Same as :class:`ModelChoiceField.to_field_name`.

Creating custom fields

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