Existing Wording: However in order to support various implementation limitations, servers SHOULD support the optional _format parameter to specify alternative response formats by their MIME-types. This parameter allows a client to override the header value when it is unable to set it correctly due to internal limitations. For the_format parameter, the values "xml", "text/xml", "application/xml", and "application/xml+fhir" SHALL be interpreted to mean the normative XML format defined by FHIR and "json", "application/json" and "application/json+fhir" SHALL be interpreted to mean the informative JSON format.

Proposed Wording: Clients SHALL indicate their content type through standard W3C headers

Comment:

We have W3C standards for making this kind of request, and modern web browsers and devices all support the ability to set HTTP content-type headers. This feels extraneous and an unnecessary burden on the server. We should remove it.