This read-only object is the index (1-4) for a row in the SNMP access list. This lets up to four distinct IP addresses, and their subnet masks, be whitelisted for SNMP access, so an admin managing a modem from multiple locations or with a redundant NMS pair needs to populate multiple index rows rather than assuming one entry covers all legitimate managers. A site with both a primary NMS and a backup NMS at a different site would use two separate rows, keyed by two different index values, to whitelist both management stations' addresses.