!!! Overview
[{$pagename}] ([WebAuthN]) are the "WebAuthn Extension Identifier" for the [Web Authentication API] [Specification] and [SHOULD] be registered per [WebAuthn-Registries][{$applicationname}] recommends  you to consult the [The Registry Entries|https://www.iana.org/assignments/webauthn/webauthn.xhtml#webauthn-extension-ids|target='_blank']

[{$pagename}] defines the initial set of extensions to be registered in the [IANA Registry] "WebAuthn Extension Identifier" registry established by [WebAuthn-Registries]. 

These [MAY] be implemented by [User-agents] targeting broad interoperability.

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||[WebAuthn Extension Identifier]||Description||Reference||Change Controller||Notes
|[appid]|This [authentication] extension allows [WebAuthn Relying Parties|WebAuthn Relying Party] that have previously registered a [credential] using the legacy [FIDO] JavaScript APIs to request an [assertion]|[Web Authentication] Section §10.1, [FIDO] AppID Extension (appid)|[W3C_Web_Authentication_Working_Group]	
|[txAuthSimple]|This registration extension and authentication extension allows for a simple form of transaction [authorization]. A [WebAuthn Relying Party] can specify a prompt string, intended for display on a trusted device on the authenticator|[Web Authentication] Section §10.2, Simple Transaction Authorization Extension (txAuthSimple)|[W3C_Web_Authentication_Working_Group]
|[txAuthGeneri]|This registration extension and authentication extension allows images to be used as transaction authorization prompts as well. This allows authenticators without a font rendering engine to be used and also supports a richer visual appearance than accomplished with the webauthn.txauth.simple extension.|[Web Authentication] Section §10.3, Generic Transaction Authorization Extension (txAuthGeneric)|[W3C_Web_Authentication_Working_Group]	
|[authnSel]|This registration extension allows a [WebAuthn Relying Party] to guide the selection of the [WebAuthn Authenticator] that will be leveraged when creating the [credential]. It is intended primarily for [WebAuthn Relying Parties|WebAuthn Relying Party] that wish to tightly control the experience around [credential] creation.|[Web Authentication] Section §10.4, Authenticator Selection Extension (authnSel)|[W3C_Web_Authentication_Working_Group]	
|[exts]|This registration extension enables the [WebAuthn Relying Party] to determine which [[{$pagename}]] the [WebAuthn Authenticator] supports. The extension [data] is a list ([CBOR] array) of [{$pagename}] encoded as [UTF-8] Strings. This extension is added automatically by the [WebAuthn Authenticator]. This extension can be added to attestation statements.|[Web Authentication] Section §10.5, Supported Extensions Extension (exts)|[W3C_Web_Authentication_Working_Group]	
|[uvi]|This registration extension and authentication extension enables use of a user verification index. The user verification index is a value uniquely identifying a user verification data record. The UVI data can be used by servers to understand whether an authentication was authorized by the exact same [Biometric data] as the initial key generation. This allows the detection and prevention of "friendly fraud".|[Web Authentication] Section §10.6, User Verification Index Extension (uvi)|[W3C_Web_Authentication_Working_Group]	
|[loc]|The location registration extension and authentication extension provides the [WebAuthn Client Device]'s current [Geolocation] to the [WebAuthn Relying Party], if supported by the client platform and subject to user [consent].|[Web Authentication] Section §10.7, Location Extension (loc)|[W3C_Web_Authentication_Working_Group]	
|[uvm]|This registration extension and authentication extension enables use of a user verification method. The user verification method extension returns to the [WebAuthn Relying Party] which user verification methods (factors) were used for the WebAuthn operation.|[Web Authentication] Section §10.8, [User Verification Method] Extension (uvm)|[W3C_Web_Authentication_Working_Group]	
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/%!! More Information
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