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An end user can freely choose which Open ID Provider to use, and can preserve their Identifier if they switch Open ID Providers. The host of the HTML document MAY be different from the end user's OP's host.
While nothing in the protocol requires Java Script or modern browsers, the authentication scheme plays nicely with "AJAX"-style setups. The "openid2.provider" and "openid2.local_id" URLs MUST NOT include entities other than "&", "<", ">", and """.
Open ID Authentication provides a way to prove that an end user controls an Identifier. To use HTML-Based discovery, an HTML document MUST be available at the URL of the Claimed Identifier.
This means an end user can prove their Identity to a Relying Party without having to leave their current Web page. Other characters that would not be valid in the HTML document or that cannot be represented in the document's character encoding MUST be escaped using the percent-encoding (%xx) mechanism described in [RFC3986] section, these discovery tags are not the same as in previous versions of the protocol.Open ID Authentication uses only standard HTTP(S) requests and responses, so it does not require any special capabilities of the User-Agent or other client software. While the same data is conveyed, the names have changed which allows a Relying Party to determine the protocol version being used.