Django - Many to many with fixed list of choices

models.py

class Issue(models.Model):
    title = models.CharField(max_length=256)
  
class Label(models.Model):
    issue = models.ForeignKey(Issue, related_name='labels')
    NAME_CHOICES = (
        ('bug', "Bug"),
        ('feature', "Feature"),
        ('blocker', "Release blocker"),
    )
    name = models.CharField(max_length=32, choices=NAME_CHOICES)