 X.509v3 can contain other extensions depending on the community of interest other than international domain names.For broad Internet use, RFC-5280 PKIX describes a profile for fields that may be useful for applications such as encrypted email.An end user who relies on the authenticity of a certificate being presented to a browser or email has no simple way to compare a forged certificate presented (perhaps which triggers a browser warning) with a valid certificate, without also being given the opportunity to validate the DN or Distinguished Name which was designed to be looked up in an X.500 DIT.