Network Working Group                                     N. Borenstein
Request for Comments: 1437                                     Bellcore
                                                             M. Linimon
                                       Lonesome Dove Computing Services
                                                           1 April 1993

          The Extension of MIME Content-Types to a New Medium

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard.  Distribution of this memo is
   unlimited.

Abstract

   A previous document, RFC 1341, defines a format and general framework
   for the representation of a wide variety of data types in Internet
   mail.  This document defines one particular type of MIME data, the
   matter-transport/sentient-life-form type.  The matter-
   transport/sentient-life-form MIME type is intended to facilitate the
   wider interoperation of electronic mail messages that include entire
   sentient life forms, such as human beings.

   Other informally proposed subtypes, such as "non-sentient-life-form",
   "non-sentient-non-life-form", and the orthogonally necessary but
   nevertheless puzzling "sentient-non-life-form", are not described in
   this memo.

The matter-transport/sentient-life-form MIME type

   In order to promote the wider interoperability of life-bearing email,
   this document defines a new MIME content-type, "matter-transport",
   and for an initial subtype, "sentient-life-form".  This subtype was
   designed to meet the following criteria:

      1.  The syntax must be extremely simple to parse, to minimize the
      risk of accidental death due to misinterpretation of the standard.

      2.  The data format must be extremely robust, with redundancy to
      ensure that individual life forms will survive and be
      reconstituted in such a form as to be nearly indistinguishable
      from their initial state, no matter how many bizarre email
      gateways are encountered in transit.

      3.  The syntax must be extensible to allow for the description of
      all yet-undiscovered aspects of life forms which will be required

      for the transport of non-human species (e.g. dolphins, Klingons,
      or politicians).

      4.  The syntax must be compatible with SGML, so that with an
      appropriate DTD (Document Type Definition -- the standard
      mechanism for defining a document type using SGML), a general SGML
      parser could be written to parse the data structure and produce
      directives to a lifeform-reconstitution mechanism. However,
      despite this compatibility, the syntax will most likely be far
      simpler than that of full SGML (so that no SGML knowledge is
      required in order to implement it), since it is anticipated that
      the full complexities of SGML will not be necessary for the
      description of even arbitrarily complex organic life forms.

   The syntax of the new content-type is very simple, and indeed makes
   considerable sacrifice of efficiency in the interest of simplicity.
   It is assumed to describe a three-dimensional rectangular solid, with
   the height, width, and depth (calibrated in centimeters) specified as
   parameters on the content-type line.  (In general, this should be a
   cube that completely contains the life form being transported; but,
   where high bandwidth is not available, a somewhat smaller cube can be
   used, provided that facilities are known to be available at the
   recipient's end to administer the medical first aid that could be
   necessary if an individual is reconstituted sans some of its
   extremities.)  A fourth parameter gives the resolution of the matter
   scan, calibrated in Angstroms.  Thus, the following Content-type
   value:

      Content-type:  matter-transport/sentient-life-form;
              height = 200; width = 60; depth=60; resolution=10

   implies that the cube being described is 60 cm by 60 cm by 200 cm,
   and is described to a resolution of 10 Angstroms.  The resolution
   gives the quantization unit, and therefore determines the quality of
   the reproduction.  The data stream itself then consists of a readout
   of the molecule found at each location, using the given resolution.
   If the resolution is high enough that more than one molecule is found
   in a given location, the molecule whose nucleus is closest to the
   center of the cube is used.  Each molecule is described by its
   molecular formula, rendered in ASCII for maximum readability if
   matter-transport mail is inadvertently delivered to a human recipient
   and displayed on a terminal screen.  Each molecule is followed by a
   space (ASCII 32) to separate it from the subsequent molecule
   description.  Extremely long molecules may require the use of a
   content-transfer-encoding such as quoted-printable, to ensure that
   line-wrapping mail systems do not, for example, cause the unintended
   breakdown of complex proteins into their constituent elements.

   The following is a message that gives a somewhat simplified rendition
   of a well-known American politician, starting from the top:

   From:  "Nathaniel S. Borenstein" <nsb@bellcore.com>
   To: Mark Linimon <linimon@lonesome.com>
   Subject: Think hard before reconstructing
   Content-description:  Dan Quayle, low-res version
   Content-type: matter-transport/sentient-life-form
           height = 200; width = 60; depth=60; resolution=100000

   Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe  Fe
   Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe  Fe
   Fe NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 Fe
   Fe NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 Fe
   Fe NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 Fe
   Fe NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 Fe
   Fe NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 Fe
   Fe NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 Fe
   Fe NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 Fe
   Fe NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 Fe
   Fe NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 Fe
   Fe NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 Fe
   Fe NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 Fe
   Fe NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 Fe
   Fe NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 NO2 Fe
   Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe  Fe
   Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe Fe  Fe

   Obviously, a real politician's skull is more complex than pure iron,
   as is its interior, but this simplified example should give the
   general flavor of the protocol.

   (A caveat, however, in the reconstitution of Vice-Presidents of the
   United States: allegedly, some of the matter-reconstitution schemes
   currently under development are reputed to perform less than
   optimally while trying to reconstitute areas of relatively high
   vacuum; for instance, their skulls.  A recommended acceptance test
   might be to experiment with subjects whose skulls are only at partial
   vacuum, such as Vice-Presidents of Marketing.)

MHS (X.400) Gateway Considerations

   The proper behavior of a MIME/MHS gateway with regard to the
   transmission of complex multimedia messages is a topic of ongoing
   investigation under the auspices of the IETF.  The addition of matter
   transport should not significantly complicate that effort, as it is
   already necessary to specify gateway behavior for MIME types that
   have no X.400 equivalents, and matter transport is simply another

   such untranslatable type.

   However, real-world X.400 gateways might be considered to
   significantly increase the hazard that mail containing a human being
   will be rejected with a message so cryptic that the recipient deletes
   it without ever realizing that an embedded human being is enclosed.
   For this reason, it is recommended that the subject of matter
   transport be explicitly marked "for further study" in the next
   generation of the X.400 specification, X.400-1996.  This will give
   the community ample time to define a more complete specification for
   matter transport as part of X.400-2000, and possibly even a readily-
   implementable specification as part of X.400-2004, although some will
   no doubt argue that this would be too strong a break with tradition.

Implementation Considerations

   The user is cautioned against passing MIME transporter messages
   through computers equipped with the NFS file system.  A no-file space
   error caused one of the laboratory rats on our prototype system to be
   truncated to a zero-length file.  Unfortunately we had neglected to
   mount a scratch rat.  (We have decided to permanently retain the
   empty filename in his honor).

   Byte swapping problems on other storage systems can be similarly
   annoying, but should not be a problem if network byte order is always
   maintained ocrrcelty.

   Despite the authors' belief in the robustness of the protocol,
   passage of email through certain systems seems to result in the
   sentient-life-form arriving at its destination upside down, resulting
   in an annoying "thud".  The cause is still under investigation.

   Interoperation with matter-transporters using polar coordinate
   systems is discouraged, due to round-off and other algorithmic errors
   in certain ubiquitous floating-point implementations, leading to
   results which are best discreetly described as "disappointing."

   Similarly, off-by-one errors should be avoided.

   Widespread adoption of this protocol may lead to an increase in user
   demand for reliable backup systems.  More importantly, for the first
   time management may be motivated to adequately fund such systems when
   they discover the possibility that proper email backup may confer
   upon them virtual immortality.  (On the other hand, implementors
   should seriously consider the desirability of making their managers
   immortal.)

   An additional concern reflects the fact that, prior to the
   introduction of this content-type, duplicate mail delivery was a
   relatively minor nuisance.  With the mail extensions described in
   this document, however, comes the possibility that duplicate mail
   delivery will leave a user with, for example, multiple spouses or
   mothers-in-law.  The relative weights of the desire to avoid
   duplicate delivery and the desire to avoid lost mail may change
   accordingly.

Security Considerations

   Security considerations are not discussed in this memo.  However, law
   enforcement officials might wish to consider the possibility that
   this mechanism could be used by criminals, either to escape
   extradition by mailing themselves outside of a legal jurisdiction, or
   to outwait the statute of limitations by mailing themselves through
   complex mail routes with long delays.  (One supposes that they could
   also look on the bright side, and consider MIME as a possible
   approach to solving the long-standing problem of prison
   overcrowding.)

Authors

   The authors of this document may be reconstituted by feeding the
   following data to an Internet-connected MIME reader:

Content-type: multipart/mixed; boundary=NextAuthor

--NextAuthor
Content-type: message/external-body; access-type=anon-ftp;
        site=thumper.bellcore.com; directory=pub/nsb; name=nsb.flesh
Content-Description: Nathaniel Borenstein

Content-type:  matter-transport/sentient-life-form
        height = 200; width = 60; depth=60; resolution=100000
--NextAuthor
Content-type: message/external-body; access-type=anon-ftp;
        site=thumper.bellcore.com; directory=pub/nsb; name=linimon.flesh
Content-Description: Mark Linimon

Content-type:  matter-transport/sentient-life-form
        height = 200; width = 60; depth=60; resolution=100000
--NextAuthor--

Authors' Addresses

   Nathaniel Borenstein
   Bellcore Room MRE 2D-296
   445 South Street
   Morristown, NJ 07962-1910

   Phone: (201) 829-4270
   EMail: nsb@bellcore.com

   Mark Linimon
   Lonesome Dove Computing Services
   P.O. Box 20291
   Roanoke, VA 24018

   Phone: (703) 776-1004
   EMail: linimon@LONESOME.COM