Subject ID

Full Title or Meme

A Subject ID is a digital Identifier associated with some real-world Entity that has established an interchange on the internet by means of a User Agent.

Context

• Many web sites require users to have a persistent user name which is unique on their site to identify the user.
• As a general rule Web Sites, and as a practical rule Identifier or Attribute Providers require that the pseudonym be unique within their domain; thus the pseudonym@domain.tld will be a valid URI.
• Some providers will reuse Subject IDs once a connection to a real user has been broken for some specified period of time. Email addresses, in particular, typically have this characteristic. A fully compliant implementation would not reuse Subject IDs.

Solutions

• Users are often asked to use their email address or cell phone number as a local user name since the email address and phone number with country code (+1 in North America) are known to be a URI and hence unique in that context. Reuse of email and phone numbers could be an issue.

References

1. Synonyms for a Subject ID include User Name, display name, gamertag, nom de guerre, Pseudonym or (on Facebook) Fake Name subject to arbitrary termination.
2. Anonym is not used in the context of identity as it does not provide one. It may be used as the condition (Anonymous) of a user prior to accepting (1) a cookie, (2) a fixed IP address, (3) an HTTPS connection or (4) a request for an Identifier.