[This introuduction is not part of IEEE Std 802.3af-2003, IEEE Standard for Information technology— Telecommunications and information exchange between systems—Local and metropolitan area net- works— Specific requirements CSMA/CD Access Method and Physical Layer Specifications Amend- ment: Data Terminal Equipment (DTE) Power via Media Dependent Interface (MDI)]

IEEE英文原版协议802.3af部分，2003年版本。网络产品开发必备。