!!! Overview
[{$pagename}] is defined by the [Certification Authority Browser Forum] for Confirming the Applicant's control over the requested [FQDN] by relying upon the attestation to the [Registration Authority] of the Applicant to request a [Certificate] contained in a [{$pagename}]. 

[{$pagename}] is part of the [Certificate Request Process]

The [{$pagename}] [MUST] substantiate that the communication came from the Domain Contact. The [CA|Certificate Authority] [MUST] verify that the [{$pagename}] was either:
* (i) dated on or after the date of the domain validation request or 
* (ii) that the [WHOIS] data has not materially changed since a previously provided [{$pagename}] for the [Domain Name|DNS Domain] Space. 

!! 3.2.2.4.6 Agreed‐Upon Change to [Website]
Confirming the Applicant's control over the requested [FQDN] by confirming one of the following under the "/.[well-known]/[Pki-validation]" directory, or another path registered with [IANA] for the purpose of Domain Validation, on the Authorization Domain Name that is accessible by the [CA|Certificate Authority] via [HTTP]/[HTTPS] over an Authorized Port: 

* The presence of Required [Website] Content contained in the content of a file or on a web page in the form of a meta tag. The entire Required [Website] Content [MUST NOT] appear in the request used to retrieve the file or web page, or 
* The presence of the Request [Token] or Request Value contained in the content of a file or on a webpage in the form of a meta tag where the Request Token or Random Value [MUST NOT] appear in the request. 

[{$pagename}] is an [Identity Document] that is used during [Identity Proofing]

!! More Information
There might be more information for this subject on one of the following:
[{ReferringPagesPlugin before='*' after='\n' }]