This object specifies the service protected VLANs of ERP instance in a string of octets containing one bit per VLAN for VLANs 1 to 2048. If the bit is set to '1', then the VLAN is configured to be protected by the Ethernet ring protection mechanism.
Sources for this description
D-Link official switch MIBsD-Link MIB copies (LibreNMS/Observium Community)