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



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     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.




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  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" <[email protected]>
  To: Mark Linimon <[email protected]>
  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



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  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.)





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  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--








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Authors' Addresses

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

  Phone: (201) 829-4270
  EMail: [email protected]


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

  Phone: (703) 776-1004
  EMail: [email protected]

































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