Range and status

           8  7  6  5  4  3  2  1
        1  ------- Range --------
        2
        .
        .          Status
        .
        n

A number in pure binary representation ranging from 0 to 255. The number represented by the range code + 1 indicates the range of circuits affected by the message. The number of circuits affected by a group supervision message is limited to 32 or less. For the group reset messages, a circuit group query message, or a circuit query response message, this requires that the range value be 31 or less. For the group bloc king and unblocking messages the range value may be up to 255, but the number of status bits set to 1 must be 32 or less.

For the group blocking, unblocking and reset messages, range code 0 is reserved. Range code 0 is exclusively used by the circuit query and circuit query response messages.

b) Status

The status subfield contains from 2 to 256 status bits numbered from 0 to 255. Status bit 0 is located in bit position 1 of the first status subfield octet. Other status bits follow in numerical order. The number of relevant status bits in a given status subfield is equal to range + 1. Each status bit is associated with a circuit identification code such that status bit n is associated with circuit identification code m + n, where m is the circuit identification code contained in the message. The status bits are coded as follows:

-       in circuit group blocking messages
0       no indication
1       blocking

-       in circuit group blocking acknowledgement messages
0       no indication
1       blocking acknowledgement
-       in circuit group unblocking messages
0       no indication
1       unblocking
-       in circuit group unblocking acknowledgement messages
0       no indication
1       unblocking acknowledgement
-       in circuit group reset acknowledgement messages
0       not blocked for maintenance reasons
1       blocked for maintenance reasons