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Rail Industry Task Team
Electronic Parts Catalog
Document Object Classes
The Air Transport Association (ATA) has used TIFF for the standardized
interchange of raster graphics for many years in its ATA 100 and successor ATA
2100 exchange specifications. A well defined profile of TIFF 5.0 using Group IV
compression was specified and developed for raster interchange. TIFF is widely
implemented, especially 5.0, although apparently Group IV implementations are
not so widespread. TIFF 5.0 has been superseded by TIFF 6.0, but ATA's profile
of TIFF 5.0 is still a valid 6.0 profile. (TIFF 6.0 added such features as
Joint Photographic Exchange Group (JPEG) compression (which is alleged to be
poorly specified) and Tiling - useful features for electronic technical
AIT has successfully mapped ATA's TIFF 5.0 profile to TIFF 6.0 (TIFF 5.0 appears
to be a true subset of TIFF 6.0). This means that in utilizing ATA's TIFF
profile with Group IV compression, the Rail Industry will be able to use
commercially available TIFF 5.0 and TIFF 6.0 products for implementing EPCES.
With the completion of CGM:1992 Version 3, ATA declared its intention to migrate
to the CGM Tile Array element for bi-level compressed (utilizing Group IV)
raster content. Therefore development on the TIFF profile was frozen, and the
only changes henceforth are defect corrections. ATA realizes that it will take
some time for the market to supply the CGM-raster products sufficient to replace
the TIFF products. The ATA strategy is therefore a sensible one, to transition
from the old TIFF specification with its superior product availability to the
newer integrated CGM specification, as product availability becomes adequate.
- Grayscale and Color
The Rail Industry is deferring the inclusion of grayscale and color
exchanges in the EPCES until ATA's specification for CGM Tile Array with JPEG is
available. There are several factors making this an advantageous decision:
- First, the only occurrence of grayscale images (there were no instances of
color images) found in Phase II analysis of Rail Industry Parts Catalogs was in
vendor marketing material included in a few of the catalogs. This appeared to
be supplemental, not integral to the catalog.
- Second, there is no formally adopted and widely implemented solution to the
exchange of compressed color and grayscale images that has adequate product
availability and reliability.
As of this writing, JPEG registration for use in the CGM:1992 Version 3 Tile
Array element is complete, meaning that the technical standards are in place.
The corresponding ATA 2100 revision should be published in 2 to 5 months. The
first commercial products should be available within 6 months of publication
(obviously, the future is difficult to predict, but this is a reasonable
The ATA has used CGM for the interchange of vector graphics for many
years, in its ATA 100 and successor ATA 2100 exchange specifications. CGM is
the only format allowed for interchange of vector graphics (for technical
illustrations). ATA's CGM profile has evolved continuously for several years.
The original GRExchange (Graphics Exchange) was based on Version 1 CGM in ATA
100, then on Version 3 CGM in ATA 2100.
ATA was innovative in adopting the CGM:1992 Amendment 1 "Rules for
Profiles" even before their completion, and has based its 2100 CGM profile
on the Model Profile. The ATA CGM profile is the industry's most advanced and
highest quality profile, for this reason in part. This strategy has resulted in
certification testing available from The National Institute for Standards
Testing (NIST). This is a critical determinant of the success of an open
interchange program. Version 3 testing components should go on-line at NIST
before the end of 1996.
ATA has continued to develop its GRExchange with fixes and minor
improvements, and will soon be adding JPEG compression for Version 3 raster
metafiles. The main focus of ATA work now is IGExchange (Intelligent Graphics
Exchange) the utilization of Version 4 CGM to allow CGM graphics to be
better integrated into hyperlinked documents.
In the arena of technical documentation, ATA is clearly the leader in the
development and application of CGM profiles. The profiles are close to State of
the Art, and ATA's GWG committee is maintaining them well.
Because the RIF application is so similar to some of the ATA applications,
RIF has an excellent opportunity to follow the ATA CGM profile. In addition, to
the quality of the profile work, RIF will thereby be benefiting as well from the
buying clout of the aviation industry, and the certification testing service
which is being set up. The RIF deviations to the ATA profile are listed in
Section 3.5 and described in Section 184.108.40.206.
- Narrative Text
The Railroad Industry Forum made the distinction between "narrative
text" and "data". RIF regards narrative text as information that
is 'free-flowing' (unstructured) text that serves as explanation or
clarification of the catalog in part, or as a whole. Conversely, the notion of
"data" is that of highly structured information concerning specific
entities (i.e., parts) that may interface with a database or external processing
Outside a catalog's "front matter", a functional parts catalogs
should contain little narrative text. In an effort to minimize the ability to
embed maintenance and operational information in a parts catalog, the RIF
resolved to severely limit narrative text within the body of a parts catalog.
- Front Matter
Narrative text contained in the front matter
allows for general information pertinent to the catalog as a whole.
- General catalog identification
Information concerning the catalog as a whole is captured in various elements
and attributes of the root element ("rif-epc"). General Catalog
identification includes the following information:
- Original Issue Date ("rif-epc" attribute "oidate")
- Version Number ("rif-epc" attribute "rev")
- Revision Date ("rif-epc" attribute "revdate")
- Document Number (see "doc-nbr")
- Document Title (see "titleblk")
- Volume Number (see "volume-nbr")
- Document Provider Name and Address (see "provider-info")
- Supersedure/Destroy Notices (see "notice")
- Model Name/Number (see "model-name", "model-nbr")
- General Effectivity Information (see "effect")
- (see "rif-epc" and "epc-info")
- Introduction Section
The only portion of the catalog's "front" section where free-flowing
text can be authored is within the "intro" element of the DTD. While
this "intro" is considered an Introduction, it can also be considered
a "Foreword", "How to Use", "Abstract", etc. This
introductory section should not include information concerning effectivity (see
Section 220.127.116.11), Vendor Codes (see Section 18.104.22.168), Abbreviations used in the
catalog (see Section 22.214.171.124), Alphabetical Index or Table of Contents (see
Section 126.96.36.199). The RIF-EPC DTD allows for explicit tagging of this
information outside the "intro" element in an effort to provide
functional capabilities to the Electronic Parts Catalog.
Introduction Section consists of: (see "intro")
- numbered and titled paragraphs (see "topic", "subtopic")
- unnumbered untitled paragraphs (paragraph text) (see "para)
- sequential (numbered) lists, with subordinations (see "numlist")
- random (bulleted) lists, with subordinations (see "unlist")
- tables (see "table")
- graphics (see "graphic")
- footnotes within tables and text (see "ftnote" and "ftnref")
- warnings, notes, and cautions (see "warning", "caution",
- cross references (see "refext" and "refint")
- emphasized text (see "emphasis")
- revised text (see "revst" and "revend")
- Alphabetical/Numerical Index, Table of Contents
Found outside the narrative "introduction", these sections may
include opening paragraphs. However, the actual index and table of content data
should not be tagged as information. For the purpose of ensuring valid index
data, these portions should be automatically generated, based on the contents of
the EPC, at the time of processing. (see "index-sect", "toc-sect")
- Effectivity Cross Reference Information
Throughout the EPC (at the catalog , chapter, section, subsection, figure,
graphic, parts list, and part number levels), effectivity information can be
captured. For example, different part numbers may require different model
numbers; different figures provide for different car numbers. Usually, the
effectivity information can be captured directly at the appropriate point.
However, in some cases, the effectivity information (series of model numbers,
serial number ranges, etc.) is grouped and categorized (ex. "Effectivity A")
at the front of the manual, and referred to throughout the manual as a single
letter. The RIF-EPC DTD allows for the creation of these effectivity groups.
For example, suppose information concerning equipment model numbers is
provided at the beginning of the manual. One group of effectivity is identified
as "A" and covers Model numbers 8-645E, 8-645E3B, 8-645E3C, and
8-645F3B. Another group of effectivity is identified as "B" and covers
model numbers 12-645E, and 12-645E3B, and 12-645E3C.
The SGML markup for this information would be:
<EFFECT-DATA><EFFECT-CODE ID="A">A</EFFECT-CODE><MODEL-NO>8-645E</MODEL-NO><MODEL-NO>8-645E3B</MODEL-NO><MODEL-NO>8-645E3C</MODEL-NO><MODEL-NO>8-645F3B</MODEL-NO></EFFECT-DATA><EFFECT-DATA><EFFECT-CODE ID="B">B</EFFECT-CODE><MODEL-NO>12-645E</MODEL-NO><MODEL-NO>12-645E3B</MODEL-NO><MODEL-NO>12-645E3C</MODEL-NO><MODEL-NO>12-645F3B</MODEL-NO></EFFECT-DATA>
A figure found in the body of the catalog is identified as being for model
numbers defined in Effectivity Group "A". At this point, the DTD
allows for either the Effectivity Code ("A") or the individual model
numbers to be identified. To utilize the Effectivity Groups defined above, the
markup would be the following:
<FIGURE DRAW-NUMBER="f100" ID="f01"><EFFECT><EFFECT-REF EFFECT-CODE="A"></EFFECT><TITLE>ENGINE EQUIPPED AND CRANKCASE AND OIL PAN ASSEMBLY</TITLE>....
It should be noted the mapping of the effectivity codes is accomplished
through the use of the SGML Attributes for the elements "effect-code"
- List of Vendor's Code, Name, Address, Phone Number
The Catalog front matter may provide an overall list of vendors, organized
by Name, Address, and Phone Number, and referenced by a Vendor Code. Vendor
Part Numbers included in parts lists must identify the vendor code through the
use of the attribute "vendor-code" of the element "vendor-part-nbr".
The DTD provides for explicit tagging of this information, in an effort to
provide functional capabilities to the Electronic Parts Catalog. (see "vendor-list")
- List of Abbreviations
The Catalog front matter may provide a list of abbreviations, explicitly
tagged as groups of terms and definitions. (see "abbrev-list")
- List of Definitions
The catalog front matter may provide a list of definitions, explicitly
tagged as groups of terms and definitions. (see "def-list")
- Body Text
The Task Team made a concerted effort to limit the ability to incorporate
maintenance and operational information within their Electronic Parts Catalogs.
To be in concert with best Industry practices, the RIF envisions separate DTDs
developed for Functional Maintenance Manuals. However, the RIF-EPC DTD does
allow for limited narrative text in the body of an EPC, provided such text can
be 'linked' or associated with a specific figure, parts list, or part number.
The RIF-EPC DTD defines two elements to embody this narrative text: "Associated
Text" (see "assoc-text") and "Supporting Table" (see "support-table").
- Associated Text
Associated text is considered as supplemental textual information
associated with a figure, parts list, and/or an individual part number. The
SGML Element "assoc-text" is therefore an optional element within the
content model for a Figure ("figure"), a Parts List ("parts-list"),
and individual items of a Parts List ("item-group", "subitem-group").
Associated text can consist of:
- General Notes (see "general"), which can contain a title and an
numbered/unnumbered subordinated list.
- Safety Notes (see "safety"), which can contain a title and an
numbered/unnumbered subordinated list.
- Warnings (see "warning"), which can include paragraph text and/or
- Cautions (see "caution"), which can include paragraph text and/or
- Notes (see "note"), which can include paragraph text and/or
- Tables (see "table")
- Graphics (see "graphic")
- Supporting Table
The purpose of the RIF-EPC DTD is to model parts catalog information,
specifically for electronic "point-and-click" navigation. The DTD,
provided in Appendix A, appropriately models Electronic Parts Catalog
Illustrations and Parts Lists to enable simple point and click navigation to
achieve unambiguous part number identification. However, during the process of
document analysis, it was found that interpretation of supplemental physical
part characteristic information was sometimes necessary for proper part
selection. This supplemental physical part characteristic information is to be
captured in the SGML element for supporting tables (see "supporting-table").
It should be noted that tabular information indicating physical part
characteristics necessary for part selection could be encoded using the SGML
element for Associated Text (see Section 188.8.131.52). However, since such physical
part characteristic information is critical, during the part selection process,
an effective EPC processing system should handle a "Supporting Table"
differently from a general table provided as "Associated Text". The
Supporting Table is an optional element within the content model for a Parts
List ("parts-list"), and individual items of a Parts List ("item-group",
Individual part numbers can be explicitly linked to a supporting table using the
attribute value "supp-table", the value of which would be the ID value
of the "support-table" element. In addition, individual part numbers
can be explicitly linked to an individual entry within the supporting table
using the attribute value "supp-tbl-ent", the value of which would be
the ID value of a specific row in the supporting table. Once within a
Supporting Table, the attribute value "item-ref" (the value of which
would be the ID value of the "item-group" or "subitem-group"
elements) provides an explicit link back to the Parts List Item. In addition,
attribute value "parts-list-ref" (the value of which would be the ID
value of the "parts-list") provides an explicit link back to the Parts
List as a whole.
See Appendix C for Supporting Table examples.
22 January 1996 Rail Industry Task Team Release 0.91 Electronic Parts Catalog
- Part Information
The purpose of the RIF-EPC DTD is to provide part information during the
course of rail equipment maintenance and for input to Railroad accounting
applications. A basic EPC utilizes the traditional detailed parts lists ("parts-list")
to capture the information necessary for part selection. Part information which
can be encoded using the DTD includes:
- Link to figure where part is illustrated (attribute "fig-ref" for
element "parts list"; also see Section 4.6)
- Internal cross reference link to other portion of document (see "ref"
- External cross reference link to other document (see "ref" within
- Effectivity information (see Section 4.4.3 below) (see "effect"
within "item-group", "subitem-group")
- Relationship of part with it's assembly or subassembly (see "part-nbr"
attributes "higher-assem" and "assem-lvl")
- Relationship of part with it's attaching parts (see "attach-parts")
- Part description, capturing the noun (ex "Bolt"), additional
description (see "nomen-col")
- Quantity (see "qty")
- Unit of Measure (see attribute "um" for element "qty")
- Vendor Part Number and Vendor Code ("vendor-part-nbr"and
- Purchaser Item or Customer Item Number ("pur-item-nbr")
- Vendor Drawing Number (attribute "vendor-draw-nbr")
- Vendor Revision Drawing Number (attribute "vendor-rev-draw-nbr")
- Component Location Code ("comp-location")
- Revision number, revision date (attributes "rev" and "revdate")
- Supporting physical part characteristics (see "support-table")
- Drawing Data
Information about individual illustrations can be captured using various
elements and attributes defined in the RIF-EPC DTD. The element "epc-fig"
groups a figure with it's parts list in the DTD. These groups of figures and
parts list may be collected in sections or subsections of a chapter. A figure is
actually a collection of a figure title and at least one graphic image. The
seller code associated with the figure can be identified with the attribute "seller-code"
on the Figure. Drawing numbers for individual graphic images can be captured
with the "graphic" element's "draw-nbr" attribute. The
image is identified using the "graphic" element's "filename"
If the graphic is to be handled as a "foldout", the attribute value "foldout"
for the "graphic" element should indicate "yes". This is a
paper paradigm that has no relevance to an EPC, however, it will have
importance to a publishing system.
Revision number and revision date can be captured for the figure as well as the
graphic image using the "rev" and "revdate" attributes.
Effectivity information can be captured for the figure and graphic image using
the "effect" element.
Effectivity is used to associate a given set of information (illustration,
part number, etc.) to a distinct category of products, and is essential for
proper part selection. The RIF-EPC DTD allows effectivity information to be
captured at the following hierarchical levels of an Electronic Parts Catalog:
The Catalog, Chapter, Section, Subsection, Figure, Graphic Image, Parts list,
and Part Number Levels. The effectivity information that can be captured at
these levels includes:
- Model name/number (see "model-name", "model-nbr")
- Serial number (see "serial-nbr")
- Equipment number (see "equip-id-nbr")
- Lot number (see "lot-nbr")
- Serial range (see "serial-range")
- Equipment range (see "equip-id-range")
- Lot range (see "lot-range")
In an effort to provide functional capabilities to the Electronic
Parts Catalog, the low and high numbers of the serial, road, and lot ranges are
captured in attribute values "low" and "high".
Alternatively, an effectivity reference code ("effect-ref") can
reference effectivity information that was defined in the Effectivity Cross
Reference ("effect-xref") element (see Section 184.108.40.206 above).
- Physical Part Characteristics
As discussed in Section 220.127.116.11, association of part-specific data is
sometimes necessary for proper part selection. In such cases a specific part
cannot be selected based on a "point-and-click" from an illustration.
Rather, multiple part numbers are thus identified and additional information
reviewed to select the desired part (See Figure B-9 and B-10 in Phase II
Document). This additional information is to be encoded as a "supporting
table" and can be linked from the individual part numbers or from the
entire parts list.
- Revision Control
The RIF-EPC DTD provides for the tracking of revision numbers ("rev")
and revision dates ("revdate") on all hierarchical elements in the
DTD. The requirement for the identification of this revision history will have
to be defined under each specific rail vendor/ rail company contract.
The EPCES must support full 'point and click' navigation enabling the
ability to drill down to the smallest component level.
- HyTime Links
The RIF has concluded to limit the use of HyTime linking as follows:
- A figure "callout" to another figure (for visual references)
- A figure "callout" to an item-group (part number, effectivity,
HyTime provides a representation of interconnections between and within
components of information. The RIF-EPC DTD incorporates HyTime to provide
interconnection between a point on a graphic (commonly a numerical "callout")
to textual information or another graphic.
To uniformly describe a graphic, EPCES overlays the actual graphic with a
virtual 2048 x 2048 (2K x 2K) grid. Because EPCES uses a virtual grid, it is
necessary to map the actual pixel value of the graphic to the virtual grid.
This approach (mapping the actual graphic to the EPCES grid) enables the hot
spot to be display device (hardware) independent.
The graphic and hot spot may be thought of as a rectangle. A rectangle can be
described by using two points: (left, top) and (right, bottom). The EPCES
algorithm assumes that the graphic and hot spot are normalized rectangles (i.e.,
the left is a lesser value than the right and the top is a lesser value than the
- Grid and Graphic Definitions
VGh = 2048 Virtual Grid Horizontal Size
VGv = 2048 Virtual Grid Vertical Size
Wg = Width of Graphic (Horizontal)
Hg = Height of Graphic (Vertical)
GSFh = VGh/Wg Horizontal Grid Scale Factor
GSFv = VGh/Hg Vertical Grid Scale Factor
- Graphic Hot Spot
The hot spot is defined by an upper left coordinate (ULx, ULy) and a lower
right coordinate (LRx, LRy).
ULx = Upper Left Horizontal Position of Hot Spot (left of rectangle) (graphic)
ULy = Upper left Vertical Position of Hot Spot (top of rectangle) (graphic)
LRx = Lower Right Horizontal Position of Hot Spot (right of rectangle) (graphic)
LRy = Lower Right Vertical Position of Hot Spot (bottom of rectangle) (graphic)
- Translation of Graphic Hot Spot to EPCES Grid
RX = ULx * GSFh Upper Left Horizontal Position (left of rectangle)
RY = ULy * GSFv Upper Left Vertical Position (top of rectangle)
RW = (LRx * GSFh) - RX Width of rectangle (Grid)
RH = (LRy * GSFv) - RY Height of rectangle (Grid)
The following is an example of the mapping algorithm utilized by HyTime in
placing hot spots. This example illustrates how to map the actual graphic to
the EPCES grid (determine and implement the RX, RY, RW and RH) values. In this
example the desired graphic hot spot upper left coordinate (UL) is (220,360),
the lower right coordinate (LR) is (240,380) and the width and height of the
graphic is (256,512).
- First, establish relative grid scale factor:
Divide VGh by Wg (2048 / 256) = 8 (GSFh)
Divide VGv by Hg (2048 / 512) = 4 (GSFv)
- Determine upper left-corner grid hot spot coordinates:
Multiply ULx by GSFh (220 * 8) = 1760 (RX)
Multiply ULy by GSFv (360 * 4) = 1440 (RY)
- Determine lower right-corner grid hot spot coordinates:
Multiply LRx by GSFh (240 * 8) = 1920
Multiply LRy by GSFv (380 * 4) = 1520
- Obtain the grid hot spot Width (RW) and Height (RH) values:
Subtract RX from (LRx * GSFh) 1920 - 1760 = 160 (RW)
Subtract RY from (LRy * GSFv) 1520 - 1440 = 80 (RH)
The following is the HyTime encoding which implements the above sample hot
<GRAPHIC FILENAME=figure1> <HOT SPOT ID=ID1.SPOT IDREF="ID1.TEXT" GRAPHIC=figure1 RX="1760"
RY="1440" RW="160" RH="80"><!(if there were multiple hot spots they would continue to be described as follows:)> <HOT SPOT ID=ID2.SPOT IDREF="ID2.TEXT" GRAPHIC=figure1 RX=...
<HOT SPOT ID=ID3.SPOT IDREF="ID3.TEXT" GRAPHIC=figure1 RX=...
<HOT SPOT ID=ID4.SPOT IDREF="ID4.TEXT" GRAPHIC=figure1 RX=...
- DTD Navigational "Links"
With the exception of linking to/from a figure 'hot spot', the functional "point-and-click"
capabilities of an Electronic Parts Catalog will be accomplished by normal
interpretation of the data constructs defined in the DTD. The content models
for the hierarchical elements within an Electronic Parts Catalog Chapter allow
for navigation and 'linking' to subordinate elements. For example:
- The content model for "chapter" allows for navigation of it's
- The content model for "epc-fig" allows for linking of a figure
with its parts list.
- The content model for "figure" allows for linking of graphics
with associated text.
- The content model for "parts-list" allows for linking of part
numbers with its supporting table and associated text.
- SGML ID/IDREF "Links"
In addition, the DTD allows for explicit linking between some of the above
elements by use of ID/IDREF attribute values. By using ID/IDREFs, it is not
always necessary to interpret the DTD model to access desired information. In
addition, sometimes cross referencing relationships cannot be achieved by DTD
Navigation. The DTD uses ID/IDREF links in the following cases:
- A Part Number ("part-nbr") can be linked to a figure via
navigation of the DTD, or by use of the "fig-ref" attribute.
- A Part Number ("part-nbr") can be linked to physical part
characteristics identified in a Supporting Table (see Section 18.104.22.168) by use of
the "supp-table" attribute.
- The part number can also be linked to a specific row in the supporting
table by use of the "supp-tbl-ent" attribute.
- A Part Number can be linked to the part number for it's higher assembly by
use of the "higher-assem" attribute.
As described in Section 22.214.171.124, effectivity information defined in the "effect-xref"
(Effectivity Cross Reference) Section can be referenced in the body of the EPC
by use attribute "effect-code" of the element "effect-ref".
Cross references to other portions of the catalog are achieved by use of
the "Internal Cross Reference" ("refint") element. The
attribute value "refid" for the element "refint" provides a
link to any element within the tagged file with the attribute "id"
with the same value. The attribute "reftype" for element "refint"
provides information on the purpose of the cross reference. The possible types
of reference include:
- ADR - Additional Detail Reference. A lateral reference to other figures in
the EPC displaying additional related details.
- DBR - Detail Breakdown Reference. A reference to a figure in the EPC
containing a breakdown of the part number in the part number field.
- ILR - Illustration Reference. A reference to another figure in the EPC
which displays related coverage.