Overview of EPCES Techniques

Rail Industry parts catalog information consists of Text; Data (parts information); Images (raster representations of drawings or pictures); and Drawings (vector formatted drawings). Each of these information "objects" has special treatment in the EPCES as follows:

SGML

Standard Generalized Markup Language (SGML) is utilized by the EPCES to encode text, data and provide for the linking of information elements. SGML, an International Standard, provides an unambiguous syntax for describing whatever a user chooses to identify within a document.

An SGML DTD provides the structure that categorizes all information in an SGML encoded document. A tighter DTD structure yields a more reliable information exchange by reducing ambiguity in encoding documents. In the course of defining the EPCES, it was agreed to develop a tightly structured DTD by applying the following guidelines:

Focus markup (define data elements) on the content of traditional OEM parts catalogs (as opposed to Industrial Supply catalogs and maintenance manuals).
Provide a structure that accommodates a minimal use of text - typical of over 80% of the Rail Industry parts catalogs reviewed in Phase II.
Pattern the best practices of other Industry DTD's when applicable to the EPCES.

TIFF

The EPCES specifies ATA's Tagged Image File Format (TIFF) 5.0 profile with CCITT Group IV compression for the exchange of bi-tonal images. ATA's TIFF specification is a subset of TIFF 5.0. Further, ATA's TIFF specification is a subset of TIFF 6.0. Therefore both TIFF 5.0 and 6.0 products support the EPCES. However, as EPCES is implementing a subset of TIFF, TIFF compliant products may generate non-EPCES compliant graphics.

The initial release of EPCES does not specify the encoding of grayscale or color Images. There are noted difficulties with TIFF 6.0 compression specifications.

CGM

The EPCES specifies ATA's profile for Computer Graphics Metafile (CGM) Version 3 for the exchange of vector information.

There are two exceptions to the Rail Industry's adaptation of ATA's profile for CGM:

First, the EPCES prohibits the use of drawing layers. Although layered drawings are potentially useful in an EPC, the lack of definition of the meaning of layers in the ATA specification allows for ambiguity and hence, an inability to exchange layering information without negotiation of layer definitions in every exchange.
Secondly, the EPCES is not allowing the use of "any" fonts beyond the baseline of fonts listed in the ATA specification.

Navigation

RIF requirements for the EPCES are that users have "point and click" drill down, from major component to minor component information. When an individual part is visually identified, users must have the capability to navigate to that specific part's data. This drill down capability requires that drawings, images, text and data (parts information) be logically interconnected or "linked". SGML encoding and an SGML application, HyTime, support the exchange of these navigational links.

SGML Linking

The RIF-EPC DTD, by means of it's hierarchical and by ID/IDREF cross referencing allows linking an information element (drawing, text, data) to another information element, and thus provides drill down capability.

HyTime Linking

Essential to an EPC application is the capability to select a graphical "call-out" resulting in a link to information specific to that "call-out". EPCES defines a coordinate system utilizing HyTime tools specifically for (and restricted to) the linking of graphics "call-outs" to other EPCES information.

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Commercial Support

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Tools

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• SGML Authoring and Viewing Tools

  In addition to being compliant to the ISO 8879-1986 specification, EPCES SGML tools must have HyTime capabilities. There is an emerging base of SGML tools with HyTime, but as HyTime implementations are relatively new it will be important to specifically request this capability.

  • SoftQuad Inc.
    56 Aberfoyle Crescent
    Toronto, Ontario
    Canada M8X 2W4
    (416)239-4801
• CGM Conversion and Verification Tools
  In the selection of graphics tools, publishers and users will want to ensure the software tool's compliance to ATA 2100.
  • Henderson Software, Inc.
    1919 14th Street, Suite 610
    Boulder, CO 80306
    (303)442-6570
    
• TIFF Reference lists
  TIFF 5.0 and 6.0 (current revision) tools will produce EPCES compliant files.
  • Imaging Magazine, Vol 4, Number 9, September 1995, "Visual Basic Toolkits",P54

  • Imaging Magazine, Vol 4, Number 3, March 1995, "C-Level Toolkit Update", P26
    
• MIL-STD-1840B Tools

  • SAIC
    1321 Research Park Drive
    Dayton, OH 45432
    George Elwood
    (513)257-3085 x358

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Documentation

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• SGML and CGM Standards

  • International Organization for Standardization
    11 West 42nd Street, 13th Floor,
    NY, NY 10036
    

  • American National Standards Institute
    11 West 42nd Street, 13th Floor,
    NY, NY 10036
    

  • ATA Graphics Working Group(ATA CGM Profile)
    The Boeing Company
    PO Box 3707, MS 2L-17
    Seattle, WA 98124
    Dave Cruikshank
    (206)544-8876
    
• TIFF Standard
  • Aldus Corporation
    Aldus Developers Desk
    411 First Ave, South
    Seattle, WA 98104-2871
    (206)628-6593

  • ATA Graphics Working Group(ATA TIFF Profile)
    The Boeing Company
    PO Box 3707, MS 2L-17
    Seattle, WA 98124
    Dave Cruikshank
    (206)544-8876

• MIL-STD-1840B
  • SAIC
    1321 Research Park Drive
    Dayton, OH 45432
    George Elwood
    (513)257-3085 x358

  • Standardization Documents Order Desk
    Building 14D
    700 Robbins Avenue
    Philadelphia, PA 19111-5094

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Compliance Assistance

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• SGML Standard

  • National Institute of Standards and Technology (NIST)
    Technology Building
    Gaithersburg, MD 20899
    Lynne S. Rosenthal
    (301)975-3353

  • SoftQuad Inc. (EPCES DTD Compliance)
    56 Aberfoyle Crescent
    Toronto, Ontario
    Canada M8X 2W4
    (416)239-4801

• CGM Standard

  • Henderson Software, Inc. (NIST Certified)
    1919 14th Street, Suite 610
    Boulder, CO 80306
    (303)442-6570

  • ATA Graphics Working Group(ATA CGM Profile)
    The Boeing Company
    PO Box 3707, MS 2L-17
    Seattle, WA 98124
    Dave Cruikshank
    (206)544-8876

• TIFF Standard

  • ATA Graphics Working Group(ATA TIFF Profile)
    The Boeing Company
    PO Box 3707, MS 2L-17
    Seattle, WA 98124
    Dave Cruikshank
    (206)544-8876

  • Aldus Corporation
    Aldus Developers Desk
    411 First Ave, South
    Seattle, WA 98104-2871
    (206)628-6593

• MIL-STD-1840B

  • SAIC
    1321 Research Park Drive
    Dayton, OH 45432
    George Elwood
    (513)257-3085 x358

  • Naval Surface Warfare Center
    Carderock Div., Code 183
    Bethsda, MD 20084-5000
    Harry Whittaker
    (301) 227-3388