!!! Overview
[{$pagename}] is used to convey to the [Service Provider] additional information in determining the [Level Of Assurance] for an [Authentication] [request].[{$pagename}] permits the augmentation of [Assertions] with additional information pertaining to the [authentication] of the [Principal] at the [Identity Provider (IDP)].If a [Relying Party] is to rely on the [authentication] of a principal by an [Identity Provider (IDP)], the [Relying Party] may require information additional to the [assertion] itself in order to assess the level of [Assurance] they can place in that [assertion]. The [{$pagename}] concept is for the [Identity Provider (IDP)] to provide to the [Relying Party] this additional information. [{$pagename}] is defined in [SAML][1] and [OpenID Connect][2][{$pagename}] specifies a set of [Policies|Policy] that [authentications] are being requested to satisfy. These [Policies|Policy] can often be satisfied by using a number of different specific [{$pagename}], either singly or in combination. 

!! [OpenID Connect]
[{$pagename}] is a Set of [Authentication Methods] or [Authentication] procedures that are considered to be equivalent to each other in a particular [context].

The [Authentication Context Class Reference] ([acr]) are defined in as a response parameter for the [Identity Token].

!! [acr], [acr_values], [default_acr_values] and [acr_values_supported]
Each of these [Authentication Context Class Values] should be in agreement and all parties should agree on which values will be used.

* [acr_values_supported] - populated in [OpenID Connect Discovery] for the [Identity Provider (IDP)] 
* [acr] - [Authorization Server] as a [Claim] value returned in the [Identity Token]
* [acr_values] - request by the [OAuth Client] in the [Authentication Request]
* [default_acr_values] - populated by the [OAuth Client] in [OAuth 2.0 Client Registration]

!! [Authentication Context Class Values]
[Authentication Context Class Values] we have been able to find.

!! [Security Assertion Markup Language] ([SAML])
[{$pagename}] are defined in section 3.4 of the Authentication Context for the OASIS Security Assertion Markup Language (SAML) V2.0 Specification[1] in [XML] Schema documents.

Only a subset of the [{$pagename}]es defined in this specification is supported by [ADFS] 2.0.

!! More Information
There might be more information for this subject on one of the following:
[{ReferringPagesPlugin before='*' after='\n' }]
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* [#1] - [Authentication Context for the OASIS
Security Assertion Markup Language (SAML) V2.0|https://docs.oasis-open.org/security/saml/v2.0/saml-authn-context-2.0-os.pdf|target='_blank'] - based on information obtained 2005-04-10