Accept-Datetime header field in HTTP

Question

I found on wikipedia that Accept-Datetime header field is "Acceptable version in time".

It isn't really clear to me what is the meaning of that field and what does it really provide?

Answer 1

Accept-Datetime header is an HTTP header, not HTML. It is not a standard header according to HTTP specifications. You should consult the specific descriptions of this header in the applicable drafts or documentation, such as the informational RFC 7089, which describes it as follows:

The "Accept-Datetime" request header is transmitted by a user agent to indicate it wants to access a past state of an Original Resource. To that end, the "Accept-Datetime" header is conveyed in an HTTP request issued against a TimeGate for an Original Resource, and its value indicates the datetime of the desired past state of the Original Resource.