This configuration parameter defines the assumed electrical length of cables (E-side cables) connecting exchange-based DSL services to a remote flexibility point (cabinet), that hosts the xTU-C that is subject to spectrally shaped downstream power back- off (DPBO) depending on this length. The electrical length is defined as the loss (in dB) of an equivalent length of hypothetical cable at a reference frequency defined by the network operator or in spectrum management regulations. This parameter shall be coded as an unsigned integer representing an electrical length from 0 dB (coded as 0) to 255.5 dB (coded as 511) in steps of 0.5 dB. All values in the range are valid. If this parameter is set to '0', the DPBO shall be disabled.