This read-create octet string encodes the second 2048 bits of a 4096-bit vector identifying which SVLAN IDs (2049 through 4094) are assigned to this service instance, where each set bit marks an assigned SVLAN. An admin sets this bit vector alongside hh3cEvcSrvInstSvlanIdListLow when the service instance needs to match SVLAN IDs in the upper range, completing the full 4096-SVLAN address space coverage. For example, setting the bit corresponding to SVLAN 3000 in hh3cEvcSrvInstSvlanIdListHigh assigns that upper-range SVLAN to this service instance.