# cf.Field.insert_aux

`Field.``insert_aux`(item, key=None, axes=None, copy=True, replace=True)

  Insert an auxiliary coordinate object into the field.

  See also

  `insert_axis`, `insert_measure`, `insert_data`, `insert_dim`, `insert_ref`

  Parameters: | item: `cf.AuxiliaryCoordinate` or `cf.DimensionCoordinate` The new auxiliary coordinate object. If it is not already a auxiliary coordinate object then it will be converted to one. key: `str`, optional The identifier for the item. By default a new, unique identifier will be generated. axes: sequence of `str`, optional The ordered list of axes for the item. Each axis is given by its identifier. By default the axes are assumed to be `'dim0'` up to `'dimM-1'`, where `M-1` is the number of axes spanned by the item. copy: `bool`, optional If False then the item is not copied before insertion. By default it is copied. replace: `bool`, optional If False then do not replace an existing auxiliary coordinate object of domain which has the same identifier. By default an existing auxiliary coordinate object with the same identifier is replaced with item.
  Returns: | out: `str` The identifier for the inserted item.
  Examples: |

      >>>