#### Description:

This attribute contains a string which identifies the physical domain of the coordinate system that a Frame describes.

The Domain attribute also controls how a Frame behaves when it is used (by astFindFrame) as a template to match another (target) Frame. It does this by specifying the Domain that the target Frame should have in order to match the template. If the Domain value in the template Frame is set, then only targets with the same Domain value will be matched. If the template`’` s Domain value is not set, however, then the target`’` s Domain will be ignored.

Type:

  String.

#### Applicability

##### Frame

The default Domain value supplied by the Frame class is an empty string.

##### SkyFrame

The SkyFrame class re-defines the default Domain value to be `"` SKY`"` .

##### CmpFrame

The CmpFrame class re-defines the default Domain value to be of the form `"` <dom1 >- <dom2 >`"` , where <dom1 > and <dom2 > are the Domains of the two component Frames. If both these Domains are blank, then the string `"` CMP`"` is used as the default Domain name.

##### FrameSet

The Domain attribute of a FrameSet is the same as that of its current Frame (as specified by the Current attribute).

##### SpecFrame

The SpecFrame class re-defines the default Domain value to be `"` SPECTRUM`"` .

##### DSBSpecFrame

The DSBSpecFrame class re-defines the default Domain value to be `"` DSBSPECTRUM`"` .

##### FluxFrame

The FluxFrame class re-defines the default Domain value to be `"` FLUX`"` .

##### SpecFluxFrame

The FluxFrame class re-defines the default Domain value to be `"` SPECTRUM-FLUX`"` .

##### TimeFrame

The TimeFrame class re-defines the default Domain value to be `"` TIME`"` .

#### Notes:

- All Domain values are converted to upper case and white space is removed before use.

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