This is a plain numeric index, ranging from 1 to 65535, that uniquely identifies one row in the table of Stormshield autoupdate subsystems, with no meaning of its own beyond distinguishing rows. Administrators don't read this value for information directly; SNMP tools use it to walk the table and correlate a given index with its matching subsystem name, state, and last-update-date columns. For example, index 3 might line up with the antivirus signature subsystem's status and last-run date in the same row.