rfc1895.txt

著名的RFC文档,其中有一些文档是已经翻译成中文的的.

Network Working Group                                        E. Levinson
Request for Comments: 1895                     Accurate Info. Sys., Inc.
Category: Informational                                    February 1996


                 The Application/CALS-1840 Content-type

Status of this Memo

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

Abstract

   This memorandum provides guidelines for using the United States
   Department of Defense Military Standard MIL-STD-1840, "Automated
   Interchange of Technical Information," with the Internet electronic
   mail standards, RFC 822 and RFC 1521.  Electronic mail provides a
   more convenient mechanism that delivery via physical media for
   certain types and quantities of data.  Software already exists to
   support data exchanges based on MIL-STD-1840 and it can continue to
   be used in conjunction with electronic mail exchanges defined in this
   document.  This document defines a new media type and a MIME message
   structure for exchanging data in conformance with MIL-STD-1840.

1.  Introduction

   The United States Department of Defense (DOD) has defined a standard,
   MIL-STD-1840 [1840], for the exchange of digital data.  Most
   applications of that standard use 9-track tape as the transport
   medium.  The Application/CALS-1840 media-type is proposed to
   facilitate such exchanges using the Multipurpose Internet Mail
   Extensions [MIME] and network based transport media, i.e. electronic
   mail [822].

   This memo has been reviewed and authorized by the Continuous
   Acquistion and Life-cycle Support (CALS) Industry Steering Group
   (ISG).  CALS is a US DOD initiative for the use and exchange of
   digital data.  The Industry Steering Group, which consists of members
   drawn from government and industry, guides the development of CALS
   standards such as [1840].

2.  Definition

   An [1840] exchange consists of a set of files with well defined file
   names (see below).  Each set consists of a declaration file and one
   or more data files.  The data files, in turn, consist of header



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RFC 1895                       CALS-1840                   February 1996


   records immediately followed by the data.  The data itself may be
   formatted in accordance with a published specification or a
   contractual agreement.

   MIL-STD-1840 encodes the file's data type in the file name.

   It might seem appropriate to transform the 1840 headers into MIME
   headers and use the appropriate media type, essentially transforming
   the 1840 files into MIME body parts.  There are three reasons for not
   doing that.  First, not all of the "types" used in [1840] are
   registered MIME types.  Second, there exists an installed base of
   software capable of reading the 1840 formatted files and processing
   the data appropriately.  Finally the three existing revisions to the
   standard have maintained the same file structure.  Consequently, a
   processor for the data may be able to handle any one of the
   standard's revisions.  Thus, a single Application/CALS-1840 is being
   proposed and its body part body contains headers and data in the
   [1840] format.

   A set of related files constitutes a "transfer unit" in 1840 and each
   transfer unit shall correspond to a Multipart/Mixed MIME entity.
   Included in each transfer unit is a declaration file which shall be
   the first body part in the Multipart/Mixed entity.  Several transfer
   units may be included in a single MIME message.



























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RFC 1895                       CALS-1840                   February 1996


2.1  Registration Information

   The following form is copied from RFC 1590, Appendix A for the
   purpose of registering this media-type.

   To:  [e-mail]
   Subject:  Registration of new Media Type content-type/subtype

   Media Type name:           Application
   Media subtype name:        CALS-1840
   Required parameters:       filename, version
   Optional parameters:       None
   Encoding considerations:   Any valid MIME encodings my be used
   Security considerations:   Depends solely on the referenced type
   Published specification:   This document
   Person & email address
   to contact for further
   information:               Alan Peltzman <[e-mail]>
                              [phone]
                              Defense Information Systems Agency
                              Center for Standards
                              Code JIEO/JEBEB
                              10701 Parkridge Blvd
                              Reston, VA 22091-4398

2.2.  The Filename Parameter

   The filename parameter gives the transfer unit filename as defined by
   [1840].  The parameter's value, called <1840-name>, has the syntax
   given by the grammer below.

        1840-name  := "D" 1840-tuseq [ 1840-type 1840-dfseq ]
        1840-type  := letter ; limited to the set defined in
                             ; the appropriate version of
                             ; [1840, Table III]
        1840-tuseq := 1840-seq
        1840-dfseq := 1840-seq
        1840-seq   := alphnum alphnum alphnum
        alphanum   := letter / digit
        letter     := "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"
        digit      := "0" / "1" / "2" / "3" / "4" / "5" /
                      "6" / "7" / "8" / "9" /






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RFC 1895                       CALS-1840                   February 1996


   All Application/CALS-1840 body parts in a single Multipart/Mixed MIME
   entity shall have the same <1840-tuseq>.  Within a single message all
   filename values shall be unique.

   Notes: 1) Tuseq and dfseq correspond to transfer unit sequence number
   and data file sequence number respectively.  2) The filename for a
   declaration file has the form "D" 1840-tuseq and for data files, the
   form "D" 1840-tuseq <letter> 1840-dfseq.

2.3.  The Version Parameter

   The specversion parameter's value shall indicate the particular
   version of MIL-STD-1840 to which the data conforms.  Valid values
   are:

        MIL-STD-1840C, 0, 199XXXXX
        MIL-STD-1840B, 0, 19921103
        MIL-STD-1840A, 0, 19871222

   Notes: (1) The value "199XXXXX" is to be replaced with the actual
   issue date for MIL-STD-1840C. (2) The embedded blanks in the above
   strings are required, hence the value must be enclosed in quote marks
   (").

3. Example

   In the example below a single transfer unit is provided.  It consists
   of three data files, the declaration, a contract defined file and an
   IGES file.  The headers and data are in accordance with MIL-STD-
   1840B.  The content-transfer-encoding perserves the data file's fixed
   record length.

        To:   [e-mail]
        From: [e-mail]
        Date: Fri, 03 Nov 1995 18:23:10 -0500
        MIME-Version: 1.0
        Content-Type: Multipart/Mixed;
            Boundary="DISA CFS - SFC ASID"

        --DISA CFS - SFC ASID
        Content-Type: Application/CALS-1840; filename=D001;
            version="MIL-STD-1840B, 0, 19921103"
        Content-Transfer-Encoding: Base64

        [Declaration File]
        --DISA CFS - SFC ASID
        Content-Type: Application/CALS-1840; filename=D001A001;
            version="MIL-STD-1840B, 0, 19921103"



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RFC 1895                       CALS-1840                   February 1996


        Content-Transfer-Encoding: Base64

        [Data File -- Contract Defined including headers]
        --DISA CFS - SFC ASID
        Content-Type: Application/CALS-1840; filename=D001Q001;
            version="MIL-STD-1840B, 0, 19921103"
        Content-Transfer-Encoding: Base64

        [Data File -- Raster including 1840 headers]
        --DISA CFS - SFC ASID--

4.  Security Considerations

   None of the body parts, as constitued, represent executable data.
   When the 1840 file format is processed the resultant data may be
   executable.  Processing will be under the control of the process
   associated with Application/CALS-1840.

   Classified information or other information that cannot be disclosed
   except to authorized personnel should not be sent via the Internet
   without using appropriate privacy enhancements, [PEM], [MOSS], or
   other privacy mechanism.

5.  Acknowledgments

   The author acknowledges the encouragement of Alan Peltzman, US DOD,
   DISA, and the suggestions of Richard Klobuchar, SAIC.

   This work was supported under U.S. Dept. of the Army, Contract
   DAAB07-93-D-T001 and prepared under the direction of the MIL-STD-1840
   Revision C Review Team.

6.  References

   [1840]      MIL-STD-1840B, "Automated Interchange of Technical
               Information", US Department of Defense, 3 November 1992.

   [822]       Crocker, D., "Standard for the Format of ARPA Internet
               Text Messages", STD 11, RFC 822, UDEL, August 1982.

   [MIME]      Borenstein, N. and N. Freed, "MIME (Multipurpose Internet
               Mail Extensions): Mechanisms for Specifying and
               Describing the Format of Internet Message Bodies", RFC
               1521, Bellcore and Innosoft, September 1993.

   [MOSS]      Crocker, S., Freed, N., Galvin, J., and S. Murphy, "MIME
               Object Security Services", RFC 1848, Cybercash, Innosoft,
               TIS, October 1995.



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RFC 1895                       CALS-1840                   February 1996


   [PEM]       Linn, J., "Privacy Enhancement for Internet Electronic Mail:
               Part I: Message Encryption and Authentication Procedures",
               RFC 1421, IAB IRTF PSRG, IETF PEM WG, February 1993.

9.  Author's Address

   Edward Levinson
   Accurate Information Systems, Inc.
   2 Industrial Way
   Eatontown, NJ  07724-2265
   USA

   Phone: [phone]
   EMail: [e-mail]





































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