As an example the use case Archiving versions, the user agent
sends the initial request:
curl --location --request GET 'www.archive.example.com/file/45' \
--header 'Accept-Datetime: Tue, 20 Mar 2001 20:35:00 GMT'
And the final URI-M answers with the response:
HTTP/1.1 200 OK
Date: Thu, 25 Oct 2021 12:06:51 GMT
Memento-Datetime: Tue, 20 Mar 2001 13:36:10 GMT
Link: ; rel="original timegate",
; rel="timemap";
type="application/link-format" ; from="Tue, 15 Sep 2011 11:28:26 GMT" ;
until="Wed, 20 Jan 2021 09:34:33 GMT"
Content-Length: 23364
Content-Type: text/html
...
Other organization such as OCF (Open Connectivity Foundation)
states in its specification that the client and server must negotiate in
the beginning payload version to understand each other, and it defines the
headers OCF-Accept-Content-FormatVersion and
OCF-Content-Format-Version, in the OCFCore Specification [56].