# Revision of an object
class Revision(models.Model):
        revision        = models.PositiveIntegerField()

# Tagging of objects
class Tag(models.Model):
        tag             = models.SlugField()

# Photo object
class Photo(models.Model):
        photo           = models.ImageField(upload_to="images/")
        priority        = models.PositiveIntegerField()
        tags            = models.ManyToManyField(Tag)
        revision        = models.OneToOneField(Revision)