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 TIFF 5.0 has been superseded by TIFF 6.0, but ATA's profile of TIFF 5.0 is still a valid 6.0 profile.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 documentation).
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.
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 estimate).
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.
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:
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 18.104.22.168), Vendor Codes (see Section 22.214.171.124), Abbreviations used in the
catalog (see Section 126.96.36.199), Alphabetical Index or Table of Contents (see
Section 188.8.131.52). 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.
The EPC Introduction Section consists of: (see "intro")
<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>.... </FIGURE>
Associated text can consist of:
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 184.108.40.206). 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", "subitem-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.
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.
Alternatively, an effectivity reference code ("effect-ref") can reference effectivity information that was defined in the Effectivity Cross Reference ("effect-xref") element (see Section 220.127.116.11 above).
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 bottom).
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
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)
RX = ULx * GSFh Upper Left Horizontal Position (left of rectangle) (Grid) RY = ULy * GSFv Upper Left Vertical Position (top of rectangle) (Grid) RW = (LRx * GSFh) - RX Width of rectangle (Grid) RH = (LRy * GSFv) - RY Height of rectangle (Grid)
Divide VGh by Wg (2048 / 256) = 8 (GSFh) Divide VGv by Hg (2048 / 512) = 4 (GSFv)
Multiply ULx by GSFh (220 * 8) = 1760 (RX) Multiply ULy by GSFv (360 * 4) = 1440 (RY)
Multiply LRx by GSFh (240 * 8) = 1920 Multiply LRy by GSFv (380 * 4) = 1520
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 spot:
<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=... <GRAPHIC>
As described in Section 18.104.22.168, 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: