This read-create StorageType indicates how this IP address row's configuration is stored, and per the description, a value of 'permanent' means no objects in that row are required to be modifiable. Admins check this to know whether a given address entry will survive a reboot (non-volatile) or vanish (volatile), and whether it can even be edited afterward if marked permanent. For example, before attempting to change an address's prefix length via SNMP, an admin would check this storage type to see if the permanent setting would block that modification.