class Reference(models.Model):
    id = models.UUIDField(verbose_name='Идентификатор', unique=False, db_index=True, default=uuid.uuid4, primary_key=True)
    name = models.CharField(max_length=255, verbose_name='Наименование', unique=False)
    short_name = models.CharField(max_length=55, verbose_name='Короткое наименование', unique=False)
    description = models.TextField(verbose_name='Описание')
    version = models.CharField(max_length=55, verbose_name='Версия', unique=True, primary_key=True)
    date = models.DateField(verbose_name='Дата начала действия')

    class Meta:
        UniqueConstraint(fields=('id', 'version'), name='id_ver')
        verbose_name = 'Справочник'
        verbose_name_plural = 'Справочники'

class Element(models.Model):
    parent_id = models.ForeignKey(Reference, on_delete=models.CASCADE, to_field='id')
    code = models.CharField(max_length=25, verbose_name='Код элемента', blank=False)
    value = models.CharField(max_length=255, verbose_name='Значение', blank=False)

    class Meta:
        verbose_name = 'Элемент'
        verbose_name_plural = 'Элементы'