[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) ( 版) <https://tools.ietf.org/html/rfc6125#section-1.8>
application service: A service on the Internet that enables
interactive and automated clients to connect for the purpose of
retrieving or uploading information, communicating with other
entities, or connecting to a broader network of services.