ieee 802.3 af

[ThisintrouductionisnotpartofIEEEStd802.3af-2003,IEEEStandardforInformationtechnology— Telecommunicationsandinformationexchangebetweensystems—Localandmetropolitanareanet- works—SpecificrequirementsCSMA/CDAccessMethodandPhysicalLayerSpecificationsAmend- ment:Da