As per Relevance of the word messages, we have this rfc below:
Network Working Group E.
Request for Comments: 2111 XIson, Inc
Category: Standards Track March 1997
Content-ID and Message-ID Uniform Resource
Status of this
This document specifies an Internet standards track protocol for
Internet community, and requests discussion and suggestions
improvements. Please refer to the current edition of the "
Official Protocol Standards" (STD 1) for the standardization
and status of this protocol. Distribution of this memo is unlimited
The Uniform Resource Locator (URL) schemes, "cid:" and "mid:"
references to messages and the body parts of messages. For example
within a single multipart message, one HTML body part might
embedded references to other parts of the same message
1.
The use of [MIME] within email to convey Web pages and
associated images requires a URL scheme to permit the HTML to
to the images or other data included in the message. The Content-
Uniform Resource Locator, "cid:", serves that purpose
Similarly Net News readers use Message-IDs to link related
together. The Message-ID URL provides a scheme, "mid:", to refer
such messages as a "resource".
The "mid" (Message-ID) and "cid" (Content-ID) URL schemes
identifiers for messages and their body parts. The "mid" scheme
(a part of) the message-id of an email message to refer to a
message. The "cid" scheme refers to a specific body part of
message; its use is generally limited to references to other
parts in the same message as the referring body part. The "mid
scheme may also refer to a specific body part within a
message, by including the content-ID's address
A note on terminology. The terms "body part" and "MIME entity"
used interchangeably. They refer to the headers and body of a
message, either the message itself or one of the body parts
in a Multipart message
Levinson Standards Track [Page 1]
RFC 2111 CID and MID URLs March 1997
2. The MID and CID URL
RFC1738 [URL] reserves the "mid" and "cid" schemes for Message-ID
Content-ID respectively. This memorandum defines the syntax
those URLs. Because they use the same syntactic elements they
presented together
The URLs take the
content-id = url-addr-
message-id = url-addr-
url-addr-spec = addr-spec ; URL encoding of RFC 822 addr-
cid-url = "cid" ":" content-
mid-url = "mid" ":" message-id [ "/" content-id ]
Note: in Internet mail messages, the addr-spec in a Content-
[MIME] or Message-ID [822] header are enclosed in angle
(<>). Since addr-spec in a Message-ID or Content-ID might
characters not allowed within a URL; any such character (
"/", which is reserved within the "mid" scheme) must be hex
encoded using the %hh escape mechanism in [URL].
A "mid" URL with only a "message-id" refers to an entire message
With the appended "content-id", it refers to a body part within
message, as does a "cid" URL. The Content-ID of a MIME body part
required to be globally unique. However, in many systems that
messages, body parts are not indexed independently their
(message). The "mid" URL long form was designed to supply
context needed to support interoperability with such systems
A implementation conforming to this specification is required
support the "mid" URL long form (message-id/content-id).
implementations can choose to, but are not required to,
advantage of the content-id's uniqueness and interpret a "cid" URL
refer to any body part within the message store
In limited circumstances (e.g., within multipart/alternate), a
message may contain several body parts that have the same Content-ID
That occurs, for example, when identical data can be accessed
different methods [MIME, sect. 7.2.3]. In those cases,
implementations are required to use the rules of the containing
entity (e.g., multi-part/alternate) to select the body part to
the Content-ID refers
Levinson Standards Track [Page 2]
RFC 2111 CID and MID URLs March 1997
A "cid" URL is converted to the corresponding Content-ID
header [MIME] by removing the "cid:" prefix, converting %hh hex
escaped characters to their ASCII equivalents and enclosing
remaining parts with an angle bracket pair, "<" and ">".
example, "mid:foo4%25foo1@bar.net" corresponds
Message-ID:
A "mid" URL is converted to a Message-ID or Message-ID/Content-
pair in a similar fashion
Both message-id and content-id are required to be globally unique
That is, no two different messages will ever have the same Message-
addr-spec; no different body parts will ever have the same Content-
addr-spec. A common technique used by many message systems is to
a time and date stamp along with the local host's domain name, e.g.,
950124.162336@XIson.com
Some
The following message contains an HTML body part that refers to
image contained in another body part. Both body parts are
in a Multipart/Related MIME entity. The HTML IMG tag contains
cidurl which points to the image
From: foo1@bar.
To: foo2@bar.
Subject: A simple
Mime-Version: 1.0
Content-Type: multipart/related; boundary="boundary-example-1";
type=Text/
--boundary-example 1
Content-Type: Text/HTML; charset=US-
... text of the HTML document, which might contain a
to the other body part, for example through a statement such as
--boundary-example-1
Content-ID: foo4*foo1@bar.
Content-Type: IMAGE/
Content-Transfer-Encoding: BASE64
Levinson Standards Track [Page 3]
RFC 2111 CID and MID URLs March 1997
R0lGODlhGAGgAPEAAP/////ZRaCgoAAAACH+PUNvcHlyaWdodCAoQykgMTk
NSBJRVRGLiBVbmF1dGhvcml6ZWQgZHVwbGljYXRpb24gcHJvaGliaXRlZC4
etc...
--boundary-example-1--
The following message points to another message (hopefully still
the recipient's message store).
From: bar@none.
To: phooey@all.
Subject: Here's how to do
Content-type: text/html; charset=
... The items in
previous message, shows how the approach you propose can
used to accomplish ...
3. Security
The URLs defined here provide an addressing or referencing mechanism
The values of these URLs disclose no more about the
environment than the corresponding Message-ID and Content-ID values
Where concern exists about such disclosures the originator of
message using mid and cid URLs must take precautions to insure
confidential information is not disclosed. Those precautions
already be in place to handle existing mail use of the Message-ID
Content-ID
4.
[822] Crocker, D., "Standard for the Format of ARPA Internet
Messages," August 1982, University of Delaware, STD 11,
822.
[MIME] N. Borenstein, N. Freed, "MIME (Multipurpose Internet
Extensions) Part One: Mechanisms for Specifying
Describing the Format of Internet Message Bodies,"
September 1993, RFC 1521.
[URL] Berners-Lee, T., Masinter, L., and McCahill, M., "
Resource Locators (URL)," December 1994.
[MULREL] E. Levinson, "The MIME Multipart/Related Content-type,"
December 1995, RFC 1874.
Levinson Standards Track [Page 4]
RFC 2111 CID and MID URLs March 1997
5.
The original concept of "mid" and "cid" URLs were part of the
Berners-Lee's original vision of the World Wide Web. The ideas
design have benefited greatly by discussions with Harald Alvestrand
Dan Connolly, Roy Fielding, Larry Masinter, Jacob Palme, and
in the MHTML working group
6. Author's
Edward
47 Clive
Metuchen, NJ 08840-1060
+1 908 549 3716
Levinson Standards Track [Page 5]
if you see any problems within the linking, don't worry be happy,
this is version 0.1 of the Relevance System and you gotta expect some crappy subroutines sometimes,
just be content we did not write this in Java, which would have made this "bigger and better" HAHAHHA.
RFC documents can be found at I.E.T.F.
Relevance System Copyright © 2002 Spectrum WorldResearch
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