# cf.AuxiliaryCoordinate.X

`AuxiliaryCoordinate.``X`

  True if and only if the coordinates are for a CF X axis.

  CF X axis coordinates are for a horizontal axis have one or more of the following:

  > - The `axis` property has the value `'X'`
  > - Units of longitude (see `cf.Units.islongitude` for details)
  > - The `standard_name` property is one of `'longitude'`, `'projection_x_coordinate'` or `'grid_longitude'`

  See also

  `ctype`, `T`, `Y`, `Z`

  Examples: |

      >>> c.Units
      <CF Units: degreeE>
      >>> c.X
      True

      >>> c.standard_name
      'longitude'
      >>> c.X
      True

      >>> c.axis == 'X' and c.X
      True