Rail Industry Task Team
Electronic Parts catalog Exchange Standard

Media Exchange - MIL-STD-1840B

The EPCES utilizes the Military Standard for Automated Interchange of Technical Information (MIL-STD-1840B) to specify file formats, naming conventions and media types for an exchange of EPC information.

ATA's MEDSPV61 was also considered. However, the ATA specification does not include file naming conventions or file formats, leaving them to be determined by exchanging parties. MIL-STD-1840B, on the other hand, includes these specifications and provides RIF the specifications for unambiguous exchange of EPC information.

MIL-STD-1840B, however, does not specify the wide variety of media that RIF is certain to utilize. MIL-STD-1840C , now in final draft mode, addresses a wide variety of media including random access and optical disk, cartridge tape and electronic transmission, overcoming this shortcoming of 1840B. Therefore EPCES specifies 1840B with additional media specifications contained in 1840C (draft). RIF will want to review and adopt the MIL-STD-1840C specification upon publication.

The requirements for packaging an EPCES exchange follow.

• Media Options
  MIL-STD-1840B specifies 9-track tape, however, allowances are made for alternative media (see 1840B, Section 5.4.2) to be negotiated by the sender and receiver. The EPCES specifies 1840B media and alternative media as listed in 1840C (draft) as follows:
  EPCES Media support as specified in 1840B:
  • 9 Track Magnetic Tape
  EPCES 1840C (draft) supports virtually all media including:
  • Cartridge Magnetic Tape (see 1840C Appendix A Section 4.2)
  • Random Access Media (see 1840C Appendix A Section 5)
    • Floppy disks
    • Removable disk drives and disk cartridges
  • CD-ROM (see 1840C Appendix A Section 5.3)
  • Electronic transfers (see 1840C, Appendix A Section 6)

  File packaging, content and naming as specified in 1840B shall be applied to all media.

• EPCES Packaging
  MIL-STD-1840B defines a three tier structure under which files are grouped. The top tier, comprising a complete exchange, is defined as a "Transfer Package". Each Transfer Package may have one or more second tier "Transfer Sets" (except sequential media where a transfer package is composed of only one transfer set). A Transfer Set is a collection of "Transfer Units" (third tier). A Transfer Unit is defined as, "[a] collection of files consisting of one transfer unit declaration file and one or more data files (the smallest collection of files to make a successful interchange of technical information)." See 1840B, Section 3.5.

  Producers of EPCES catalogs, to support the logical grouping of files, will determine the number of Sets and Units in an exchange (Transfer Package). It is expected that a typical EPCES Transfer Package will consist of one Transfer Set containing one or a small number of Transfer Units.

• SGML Document Transfer Unit
  MIL-STD-1840B, in order to support a wide variety of technical documentation, provides for five types of Transfer Units, only one of which is applicable to EPCES – the SGML Document Transfer Unit.

  An SGML Transfer Unit shall consist of the following elements:

  1. Transfer Unit Declaration File
     There shall be one Transfer Unit Declaration File to provide all information necessary to describe the transfer unit contents to the receiver. It uniquely identifies the contents and counts each file type contained in the transfer unit (see 1840B, Section 5.3.1.2).

     Figure 2 is an example of the content of the EPCES Transfer Unit Declaration File. This example is of the Transfer Unit Declaration for the Phase III deliverables (see Section 5.4 for listing of files specified in this Transfer Unit Declaration).

     version: MIL-STD-1840B, 0, 19921103
     srcsys:  AIT 979 Spaulding Ave., Grand Rapids, MI 49546
     srcdocid: EPCES Phase III documentation ver 0.91
     srcrelid: EPCES Phase III document ver 0.9
     chglvl:  ORIGINAL, 0, .01, 19960122/0900:00
     dteisu:19960122/0900:00
     dstsys: RIF, c/o Mr. Dennis Smid, Union Pacific Railroad, 1416 Dodge St., Omaha, NE 
     dstdocid: Phase III Doc 0.91
     dstrelid: Phase III Doc 0.9
     dtetrn: 19960120/1200:00
     dlvacc: RIF/AIT Amended Contract  19951009
     filcnt: G1, T2, C1, R6, X2 
     ttcls: Unclass
     doccls: Unclass
     doctyp: Final EPCES specification
     docttl: EPCES Phase III Document
     transacttyp: SGML 
     

     Figure 2

  2. Document Type Declaration File
     This optional file shall contain the EPCES identifier for the SGML document being transmitted. If this file is absent, then the document type declaration of the SGML document shall be the first data in the text source file. (see 1840B, Section 4.4.4 and this Document, Appendix A.1)
     
  3. Transfer Unit Data Files
     EPCES allows for all data files specified in 1840B with the exception of the Formatting Output Specification Instance (FOSI) data file. FOSI provides for the reproduction of hard copy output which is not specified in EPCES (see 1840B Section 4.2.3.f). The following Data Files are supported:
     1. SGML Coded Text Source File(s)
        These are SGML coded ASCII text files, marked up in accordance with EPCES. If a document type declaration file is present in the SGML document transfer unit, then the text source file shall make up the document element of the SGML transfer unit. If there is no document type declaration file, then the text source file shall make up the document type declaration set or EPCES identifier followed by the document element. (see 1840B, Section 4.4.5)
     2. Illustration file(s) in CGM or TIFF format
        "Each set of text source files for an exchange shall be supported with an illustration data file for each graphic entity in the technical publication except where there are multiple instances of the same graphic entity in different locations in the technical publication. In this situation, a single illustration data file may be used to satisfy all of the graphic entity instances." (see 1840B, Section 4.4.7)
     3. Supported Optional Files
        • SGML Text Entity File(s) (see 1840B, Section 4.2.3.d)
        • Special text files per contract, (see 1840B, Section 4.2.3.g)
        • Contract defined data files (see 1840B, Section 4.2.3.f)
• File Naming and Directory Structures
  EPCES specifies file naming as detailed in 1840B Section 5. EPCES also specifies that each data file type shall be contained within a directory for that file type. The directory name shall be the Transfer Unit Number and sub-directories shall be the Transfer Unit Number plus the letter designating file type.

  The following graphically depicts an EPCES compliant exchange (Transfer Package) for this contract's Phase III deliverables.

  
  Figure 3
• Header Records
  MIL-STD-1840B specifies each Transfer Unit data file shall have a header record. EPCES excludes this requirement. EPCES, not requiring header records, simplifies creating and interpreting an EPCES exchange. Header record requirements are also in MIL-STD-1840C however, there is current discussion of eliminating header records in subsequent releases (see 1840B, Section 5.3.2.2).

• Media Labeling
  MIL-STD-1840B specifies all media shall have a media label affixed to it. (see 1840B, Section 5.5.1). An EPCES label shall be as follows:
  • Company Name
  • Date (of transfer)
  • Version (MIL-STD-1840B, 0)
  • Provider Code
  • Volume ID (4 letter identifier chosen by publisher plus a two digit volume number)
  • Density/Capacity
  • Media number
  • Point of Contact

22 January 1996 Rail Industry Task Team Release 0.91 Electronic Parts Catalog Exchange Standard 3