title: Why is Django DecimalField attribute `max_digits` non-optional?
body: <pre><code>CommandError: System check identified some issues:
  
  ERRORS:
  (fields.E132) DecimalFields must define a 'max_digits' attribute.
  </code></pre>
  
  <p>Is there a technical reason why <code>max_digits</code> is a required attribute for Django's model field <code>DecimalField</code>?</p>
  
  <p>The docs say it used Python's <code>[decimal][1]</code> module, but python object type doesn't seem to be bothered at all by anything to do with the absolute number of digits of the decimal object. </p>
  
  <p>Maybe there's an opaque ORM reason?</p>
  
  <p><code>FloatFields</code> (against which <code>DecimalFields</code> are compared) don't require you to predetermine the number of digits so why decimals? </p>
  
  <p>I know this small additional attribute shouldn't bother me but for some reason it's seemed unnecessary to me ever since the first time I used this field type.</p>