text: """
   The GeometryColumns and SpatialRefSys models for the PostGIS backend.
  """
  from django.db import models
  from django.contrib.gis.db.backends.base import SpatialRefSysMixin
  
  class GeometryColumns(models.Model):
      """
      The 'geometry_columns' table from the PostGIS. See the PostGIS
      documentation at Ch. 4.2.2.
      """
      f_table_catalog = models.CharField(max_length=256)
      f_table_schema = models.CharField(max_length=256)
      f_table_name = models.CharField(max_length=256)
      f_geometry_column = models.CharField(max_length=256)
      coord_dimension = models.IntegerField()
      srid = models.IntegerField(primary_key=True)
      type = models.CharField(max_length=30)
  
      class Meta:
          app_label = 'gis'
          db_table = 'geometry_columns'
          managed = False
  
      @classmethod
      def table_name_col(cls):
          """
          Returns the name of the metadata column used to store the
          the feature table name.
          """
          return 'f_table_name'
  
      @classmethod
      def geom_col_name(cls):
          """
          Returns the name of the metadata column used to store the
          the feature geometry column.
          """
          return 'f_geometry_column'
  
      def __unicode__(self):
          return "%s.%s - %dD %s field (SRID: %d)" % \
                 (self.f_table_name, self.f_geometry_column,
                  self.coord_dimension, self.type, self.srid)
  
  class SpatialRefSys(models.Model, SpatialRefSysMixin):
      """
      The 'spatial_ref_sys' table from PostGIS. See the PostGIS
      documentaiton at Ch. 4.2.1.
      """
      srid = models.IntegerField(primary_key=True)
      auth_name = models.CharField(max_length=256)
      auth_srid = models.IntegerField()
      srtext = models.CharField(max_length=2048)
      proj4text = models.CharField(max_length=2048)
  
      class Meta:
          app_label = 'gis'
          db_table = 'spatial_ref_sys'
          managed = False
  
      @property
      def wkt(self):
          return self.srtext
  
      @classmethod
      def wkt_col(cls):
          return 'srtext'
  