[1]

RFC 6125 - Representation and Verification of Domain-Based Application Service Identity within Internet Public Key Infrastructure Using X.509 (PKIX) Certificates in the Context of Transport Layer Security (TLS) (2015-03-13 22:27:53 +09:00 版) https://tools.ietf.org/html/rfc6125#section-1.8

interactive client: A software agent or device that is directly controlled by a human user. (Other specifications related to security and application protocols, such as [WSC-UI], often refer to this entity as a "user agent".)