title: What is Django model field choices best practices?
body: <p>In my project I have  different apps and in models I have specific choices options separate for each <code>model.py</code>.</p>
  
  <p>Like:</p>
  
  <pre><code>size = models.CharField(max_length=1,
                            choices=SIZE_CHOICES)
  
  SIZE_CHOICES = (
      ('f','feet'),
      ('i','inches'),
      ('y','yards'),
      ('m','milimeters'),
      ('c','centimeters'),
  
  )
  </code></pre>
  
  <p>However some of same choices options are shared between all the apps. </p>
  
  <p>What is the best practise to have all the same  choices in single place? <br>
  (Ideally somewhere where end user would be able to define them and not in the code.)</p>