This read-create octet string is the plaintext authentication key referenced by its own description as used in Level 1 hello packets whenever the corresponding csIsisCircL1AuthType is set to plaintext, and like its sibling it always reads back as an empty string to keep the configured secret from being disclosed via SNMP. Despite that apparent copy-paste reference to Level 1 in the source text, it functions as the shared key an administrator provisions to authenticate hello exchanges on this Level 2 circuit. For example, an engineer would set csIsisCircL2Password identically on both ends of a backbone link so mismatched or unauthorized routers cannot silently join the adjacency.