Message Formats M1M0 M3M2 M5M4 M7M6 M9M8 TM10 MP=1Ack2 NPAck D1D0 D3D2 D5D4 D7D6 D9D8 D11D10 D13D12 D15D14 Message Next Page 0, 7FF: Reserved 1~6: Null, One UP, Two UP, One UP + RF code, OUI, PHY ID 7: 100Base-T2 8: 1000BASE-T with Two AbilityP 9~2047: Future Use S1S0 S3S2 A0S4 A2A1 A4A3 A6A5 RFA7 NPAck D1D0 D3D2 D5D4 D7D6 D9D8 D11D10 D13D12 D15D14 Base Page 0, 1F: Reserved 1: 802.3 2: 802.9 3: 802.5 4: IEEE 1394 10 100X10F T4100XF aPP RES If IEEE 802.3 Clause 28 U1U0 U3U2 U5U4 U7U6 U9U8 TU10 MP=0Ack2 NPAck D1D0 D3D2 D5D4 D7D6 D9D8 D11D10 D13D12 D15D14 Unformatted Next Page1, 1000BaseTU0, U1, Master-Slave Config U2: M Port or Single Port U3: Full Duplex U4: 1000BASE-T Half Duplex Reserved=0 T2 mutually exclusive with 1000BASE-T (single Msg Pg) Valuable Coding space is taken up by legacy and not used.