This object indicates the length of time in seconds that the spectral notch is to be maintained. The CMTS MAY make the excluded subcarriers active after the expiration of the Duration attribute. There is no expectation that CMTS will re-activate the excluded subcarriers immediately after the expiration of the timer. It is recommended that the CMTS use the OCD message to create the spectral notch. This value can only be changed while value of 'docsPnmCmtsDsOfdmNprEnable' is 'false'. An attempt to set this value while the value of 'docsPnmCmtsDsOfdmNprEnable' is 'true' will return 'inconsistentValue'.