!!! Overview
[{$pagename}] in [OpenID Connect] is an [Authorization Request] that requests that the [Resource Owner] be [authenticated] by the [Authorization Server].

The [{$pagename}] is specifically identified from an [OAuth 2.0] [Authorization Request] by the presence present __only when the "OpenID" [OAuth Scope]__ value is present. 

[OAuth 2.0] [{$pagename}] using extension parameters and [scopes|OAuth Scopes] defined by [OpenID Connect] to request that the [Human participant|Natural Person] be [authenticated] by the [Authorization Server], which is an [OpenID Connect Provider], to the [OAuth Client], which is an [OpenID Connect] [Relying Party].

[Authorization Servers] [MUST] support the use of the [HTTP GET] and [HTTP POST] methods defined in at the [Authorization_endpoint]. [OAuth Clients] [MAY] use the [HTTP GET] or [HTTP POST] methods to send the [{$pagename}] to the [Authorization Server]. If using the [HTTP GET] method, the request parameters are serialized using [URI Query String Serialization]. If using the [HTTP POST] method, the request parameters are serialized using [Form Serialization].

!! Authentication Request Validation
The [Authorization Server] [MUST] validate the [Authentication Request] received as follows:
* The [Authorization Server] [MUST] validate all the [OAuth 2.0] parameters according to the [OAuth 2.0] specification.
* Verify that a [scope|OAuth Scopes] parameter is present and contains the [openid scope] value. (If no [openid scope] value is present, the request may still be a valid [OAuth 2.0] [Authorization Request], but is not an [OpenID Connect] [{$pagename}].)
* The [Authorization Server] [MUST] verify that all the [REQUIRED] parameters are present and their usage conforms to [OpenID Connect Core 1.0] specification.
* If the [sub] (subject) [Claim] is requested with a specific value for the [id_token], the [Authorization Server] [MUST] only send a positive response if the [End-User] identified by that [sub] value has an active session with the [Authorization Server] or has been [Authenticated] as a result of the request. The [Authorization Server] [MUST NOT] reply with an [id_token] or [Access_token] for a different user, even if they have an active session with the [Authorization Server]. Such a request can be made either using an [id_token_hint] parameter or by requesting a specific [Claim] Value as described in [OpenID Connect Core 1.0] Section 5.5.1, if the [claims] parameter is supported by the implementation.

As specified in [OAuth 2.0] [RFC 6749], Authorization Servers [SHOULD] ignore unrecognized [{$pagename}] parameters.

If the [Authorization Server] encounters any [error], it [MUST] return an error response, [OpenID Connect Core 1.0] per Section 3.1.2.6.

If no errors are encountered, then the following proceeds:
* [Authorization Server] Authenticates [End-User]
* [Authorization Server] Obtains [End-User] [Consent]/[Authorization]
* [OpenID Connect Authentication Response]

!! More Information
There might be more information for this subject on one of the following:
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