The parameters defined in the standard information field represent modes of operation or capabilities that relate to the DSL modems. The standard information field is not used in all of the messages. The messages that use the standard information field include CL, CLR, MP, and MS; those that do not use the standard information field are MR, ACK, NAK, and REQ. The Par(1) parameters in the standard information field contain one NPar(1) octet and two SPar(1) octets. The NPar(1) octet identify availability or use of V.8 or V.8bis in the voice- band , and it identifies enabling of the Silent Period in the G.994.1 clear-down procedure. Together, the two SPar(1) octets identify availability or use of G.992.1 Annexes A, B, C, and/or H; G.992.2 Annexes A, B, and/or C; and G.991.2 Annexes A and/or B. Also included are code points for the multicarrier and single-carrier VDSL systems defined in the ETSI VDSL standard [5], [6] and the Committee T1 VDSL Trial Use Standard [7]. Each of the SPar(1) parameters have an array of Par(2) and Par(3) subparameters; in total there are 191 octets defined, that is, total Par(2) and Par(3) octets, in support of the SPar(1) standard information parameters. The breakdown on the distribution of octets is as follows :
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