    Network Working Group                                          D. Clunie
    Request for Comments: 3240                                 E. Cordonnier
    Category: Informational                                  DICOM Committee
                                                               February 2002

            Digital Imaging and Communications in Medicine (DICOM) -
                  Application/dicom MIME Sub-type Registration

    Status of this Memo

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

    Copyright Notice

       Copyright (C) The Internet Society (2002).  All Rights Reserved.

    Abstract

       This document describes the registration of the MIME sub-type
       application/dicom (Digital Imaging and Communications in Medicine).
       The baseline encoding is defined by the DICOM Standards Committee in
       "Digital Imaging and Communications in Medicine".

    1. DICOM Definition

       Digital Imaging and Communications in Medicine (DICOM) specifies
       protocols and formats for the exchange of images, time-based
       waveforms, reports, and associated information for medical
       applications.

       Individual DICOM objects (such as images) may be encapulsated in
       files and exchanged by e-mail using the Media Type defined herein.
       In addition, a set of DICOM files may be described by an index file,
       DICOMDIR, which may accompany the files that it references.

    2.  IANA Registration

       MIME media type name: Application

       MIME subtype name: dicom

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       Required parameters:

          "id" is constructed from a DICOM File ID (see DICOM PS3.11).  The
          total length is limited to 71 characters.  Each component is
          limited to 8 characters.  The delimiter is a forward slash "/".
          There is never a leading delimiter (i.e., this is not a
          traditional path from a root directory).

          If a DICOMDIR (which provides an index of files) is included, then
          it will refer to other DICOM files in the file set by use of this
          File ID.  The File ID is not encoded within each DICOM file.  If a
          DICOMDIR is not present, then the "id" parameter may be absent.
          Note that the DICOMDIR will also have a Media Type of
          application/dicom and is distinguished from other files by its ID
          of "DICOMDIR".

          For example:
           "ROOTDIR/SUBDIR1/MRSCAN/A789FD07/19991024/ST00234/S00003/I00023"

          Each component shall be character strings made of characters from
          a subset of the G0 repertoire of ISO 8859.  This subset consists
          of uppercase alphabetic characters, numeric characters and
          underscore.  The following characters are permissable:

          A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V,
          W, X, Y, Z (uppercase)
          1, 2, 3, 4, 5, 6, 7, 8, 9, 0 and _ (underscore)

       Optional parameters:

          none

       Encoding considerations:

          The DICOM information is binary, therefore the encoding used shall
          support lossless transfer of binary information.  Typically, the
          Content-Transfer-Encoding would be set to "Base64".

          Multiple DICOM parts should be included as a Multipart/related
          entity [2387].  Receiving agents shall also support multiple parts
          as a Multipart/mixed entity.  When multiple DICOM parts are
          included, one of the parts may be a DICOMDIR, in which case, all
          the files referred to by the DICOMDIR shall also be present.  The
          DICOMDIR is not required to be the first Application/dicom part
          encoded in the message, in which case the optional "start"
          parameter should refer to the content-id of the part containing
          the DICOMDIR.

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          Multiple DICOM Application/dicom parts may be included with other
          types of parts as a Multipart/mixed entity.

       Security considerations:

          Application/dicom parts contain medical information, including
          individual demographic information.  Accordingly, their exchange
          should be restricted to a secure network or within a secure
          wrapper that protects a patient's right to confidentiality
          according to local and national policy.  The specific security
          mechanisms are outside the scope of this proposal.  Such
          mechanisms as Secured MIME (S/MIME) [2633] or similar might be
          appropriate.

       Interoperability considerations:

          Because DICOM information is specific to the medical (imaging)
          domain, generic e-mail applications may not be able to interpret
          the information.

          The Media Type has been designed in order to allow for

          (i)   DICOM aware applications to interoperate,
          (ii)  generic applications to save the files in a form
                recognizable as DICOM files, that a DICOM application may
                subsequently use.

       Published specification:

          The Digital Imaging and Communications in Medicine (DICOM)
          Standard is a standard of the DICOM Standards Committee, published
          by the National Electrical Manufacturers Association (NEMA), 1300
          N. 17th Street, Rosslyn, Virginia 22209 USA,
          (http://medical.nema.org).

       Applications which use this media:

          Biomedical imaging applications.

       Additional information:

          1. Magic number(s): "DICM" after 128 byte preamble indicates DICOM
                                PS 3.10 file

          2. File extension(s): ".dcm" is recommended for files saved to
                                  disk (other than DICOMDIR)

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          3. Macintosh file type code:  Macintosh File Type "DICM" is
                                         recommended

          4. Object Identifiers: none

       Person to contact for further information:

          1. Name: Howard Clark
          2. E-mail: how_clark@nema.org

       Intended usage:

          Common

          Interchange of biomedical images.

       Author/Change controller:

          DICOM Standards Committee

    3. References

       [DICOM]  DICOM Standards Committee, "Digital Imaging and
                Communications in Medicine", 2001.

       [2387]   Levinson, E., "The MIME Multipart/Related Content-type", RFC
                2387, August 1998.

       [2633]   Ramsdell, B., "S/MIME Version 3 Message Specification", RFC
                2633, June 1999.

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    4. Authors' Addresses

       David Clunie
       RadPharm
       943 Heiden Road
       Bangor PA 18013
       USA

       Phone: +1-570-897-7123
       Fax:   +1-425-930-0171
       EMail: dclunie@dclunie.com

       Emmanuel Cordonnier
       Etiam
       20 rue du Pr J. Pecker
       35000 Rennes
       France

       Phone: +33(0)299 14 33 88
       Fax:   +33(0)299 14 33 80
       EMail: emmanuel.cordonnier@etiam.com

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    5.  Full Copyright Statement

       Copyright (C) The Internet Society (2002).  All Rights Reserved.

       This document and translations of it may be copied and furnished to
       others, and derivative works that comment on or otherwise explain it
       or assist in its implementation may be prepared, copied, published
       and distributed, in whole or in part, without restriction of any
       kind, provided that the above copyright notice and this paragraph are
       included on all such copies and derivative works.  However, this
       document itself may not be modified in any way, such as by removing
       the copyright notice or references to the Internet Society or other
       Internet organizations, except as needed for the purpose of
       developing Internet standards in which case the procedures for
       copyrights defined in the Internet Standards process must be
       followed, or as required to translate it into languages other than
       English.

       The limited permissions granted above are perpetual and will not be
       revoked by the Internet Society or its successors or assigns.

       This document and the information contained herein is provided on an
       "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
       TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
       BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
       HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
       MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

    Acknowledgement

       Funding for the RFC Editor function is currently provided by the
       Internet Society.

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