This preserves the actual value of the local peer identity used by an expired Phase-1 tunnel, per its description, the historical companion to HistPeerLocalType. It gives an admin the specific identity string this device presented on a now-closed connection, useful for confirming exactly what was sent during a past negotiation that's since been torn down. Comparing this recorded value against what was expected in a security review of a past incident can confirm or rule out an identity mismatch as the historical cause.