This read-only DisplayString, up to 80 characters, is described as the name of the PRF (pseudo-random function) algorithm negotiated for this SA, used internally to derive keying material. An admin reads this mainly during detailed security audits, since the PRF choice affects the cryptographic strength of derived session keys even though it's a less commonly checked field than the main encryption/hash algorithms. For example, a security auditor reviewing active tunnels might record this PRF algorithm value alongside the crypto and hash algorithms to build a complete picture of an SA's cryptographic profile.