<xsd:documentation>The The power loss for one way travel of a beam of light, usually measured
in decibels per unit length. It is necessary to include both the value (and its unit) and the
wavelength. The wavelength varies with the refractive index, while the frequency remains constant.
The wavelength given to specify this type is the wavelength in a vacuum (refractive index = 1).</xsd:documentation>
<xsd:documentation>The value of the one way loss per unit of length.
The usual uom is decibels per kilometre (dB/km), although this might vary depending on the
calibration method used.</xsd:documentation>