SONET Compliance(5) bit 7 : Unallocated bit 6 : OC-12, single mode long reach bit 5 : OC-12, single mode inter reach bit 4 : OC-12, short reach bit 3 : Unallocated bit 2 : OC-3, single mode long reach bit 1 : OC-3, single mode inter reach bit 0 : OC-3, short reach
Sources for this description
Katron / KTI official product MIB packages