This reports the type of identity the remote peer used to authenticate itself to this device for this Phase-1 tunnel, per its description - the remote-side counterpart to cisgIpsSgTunLocalType. It tells an admin exactly how the peer identified itself on this specific connection, which matters when this device's own local crypto identity matching rules need to be checked against what the peer is actually presenting. A tunnel showing the remote peer using 'userFqdn' type identity when the local policy expects to match by plain IP address would explain an authentication mismatch specific to that one peer relationship.