I agree that it is not obvious in the tutorial what the first
argument is setting. It is documented elsewhere:
https://docs.djangoproject.com/en/1.3/topics/db/models/#verbose-field-names
>class DateTimeField([auto_now=False, auto_now_add=False, **options])
>
>In the description it vaguely indicates that DateTimeField is a child
>of DateField (which has the same definition), and I see no indication
>at all that DateField is a child of Field.
The description says "Takes the same extra arguments as
DateField." I think all it implies is that it is similar to
DateField.