The Application/CALS-1840 Content-type
RFC 1895

Document Type RFC - Informational (February 1996; No errata)
Author Ed Levinson 
Last updated 2013-03-02
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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.


   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

Levinson                     Informational                      [Page 1]
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.

Levinson                     Informational                      [Page 2]
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.

   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 <>
                              +1 (703) 735-3568
                              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
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