[apps-discuss] 'Base' and 'Content-Base' header fields

[Mykyta Yevstifeyev <[e-mail]>]

Hello all,

RFC 1808 proposed the 'Base' header field to be used in HTTP/mail 
messages.  This header field was intended to be used for establishing 
the base URI when resolving relative URIs; what RFC 1808 says is:

>    Messages are considered to be composite documents.  The base URL of a
>    message can be specified within the message headers (or equivalent
>    tagged metainformation) of the message.  For protocols that make use
>    of message headers like those described in RFC 822 [5], we recommend
>    that the format of this header be:
>
>       base-header  = "Base" ":" "<URL:" absoluteURL ">"
>
>    where "Base" is case-insensitive and any whitespace (including that
>    used for line folding) inside the angle brackets is ignored.

However, this disappeared from RFC 2396.  RFC 2110, though, introduced 
'Content-Base' header field for the similar purpose, but RFC 2557, which 
obsoleted 2110, said that this header field was removed from the new 
version of MHTML.  Now 'Content-Base' for MIME is listed with reference 
to RFC 4021, which referred to then-obsoleted RFC 2110.

RFC 4229 registered 'Content-Base' for HTTP, referring to RFC 2068.  
Nevertheless RFC 2616 didn't specify 'Content-Base' header field as 
well, so the factual spec is obsolete RFC 2068.

So, you see, 'Content-Base' is in the rather uncertain state, and no 
clear definition is available.  (This reminds me of 'Link' header field, 
which was in rather the same state.)  So, is there enough support to 
undertake the effort to define 'Content-Base' field properly?

Mykyta Yevstifeyev