#### Description:

This attribute specifies the spectral position (frequency, wavelength, etc.), at which the values described by the FluxFrame are measured. It is used when determining the Mapping between between FluxFrames.

The default value and spectral system used for this attribute are both specified when the FluxFrame is created.

Type:

  Floating point.

#### Applicability

##### FluxFrame

All FluxFrames have this attribute.
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