Section 3.3

SPECIFIC CONSIDERATIONS

TDP Delivery

Potential TDP Delivery Options

Raster

Processable Data Files

TDP Delivery

The purpose of this section is to determine the status and/or existence of a TDP and ultimately to lead the project manager to a decision as to the specific type of digital data and media format required to support the programme. In addition to the immediate TDP requirements (acquire and/or develop an end item or system), the project manager should consider the potential long term engineering and support functions and requirements for technical data when selecting TDP formats.

Potential TDP Delivery Options

While actual delivery may include a mixture of options, TDP information falls into three distinctly different delivery forms:

Document (drawing image): Hard copy or digital images (raster).
Processable Data Files: CAD data and Computer-aided Engineering (CAE) systems create vector graphic files that define the geometry and associated data attributes of defence systems assemblies, subassemblies, and components. Data generated in this manner is capable of being updated; hence, the files containing data are processable. In defence system development contracts, digital delivery of processable data files is preferred and should be considered the standard of communication between the contractor and the NATO/NATO nations.
CITIS interactive access: See section 5 (CITIS) for interactive access/delivery options.

Raster

Raster data is a binary representation of an image. Raster may be thought of as the electronic version of a paper document. It contains no "intelligence" and must be reviewed through human interpretation. There are two types of raster data, tiled and untiled. Tiled raster is the preferred format because of smaller file size. A tiled raster image resembles a two-dimensional grid with each "tile" or set of pixels representing a portion of the image. Text and graphics in raster data formats are stored digitally, which allows more rapid and consistent access to the stored images than paper. In addition, raster data can be sent via electronic means to remote sites.

Raster files can be edited in several ways:

Raster Edit: The manipulation of individual pixels or pixel groups;
Vector Overlay: Hybrid editing where vectors are overlaid onto a raster file (both the raster and vector are stored as the final image);
Raster to Vector Conversion: Conversion of pixel groups to vector primitives.

Raster documents may be converted to processable text via Optical Character Recognition (OCR) technology. With the advent of raster scanning technologies, the ability to convert existing TDPs to digital data files has become available. However, the quality assurance process (by human interpretation) required to verify the data contents may increase costs substantially. Also, raster image files require a large amount of memory storage due to their file structure and contain no additional information other than each tile's position on a grid. Because of these drawbacks, the project manager should consider processable data forms before considering raster unless the TDP will not be used for competitive reprocurement.

Processable Data Files

Processable data files provide the majority of options available for digital TDP delivery. Processable data files can be broken down into two additional categories, drawing and product description data files and text data files. These categories are considered processable, because the data can be manipulated by the user, interpreted by the computer, and reprocessed into an updated or new form as specified by the user.

Drawing and Product Description Data Files

Drawing data files, the output of CAD systems, comprise vector data, and as the name "vector" implies, the image produced is composed of vectors, a sequence of line segments. Vector data provides geometrical and physical representation of objects in both two and three dimensions. Vector data files are stored digitally allowing rapid retrieval and integration into other compatible systems. Because the data consists of a sequence of line segments and patterns/symbols that represent entities with specific orientation and location, vector data can be translated to code interpreted by some automated machine tools.

Drawings delivered in this format must conform to IGES Class II (MIL-D-28000) unless the native vector CAD files are available in an agreed-to, compatible format. (The user of native vector data must have the same type of CAD system or must have a direct translator from the source system to the destination system.) The native CAD format is the preferred format during early development phases in the defence system programme's life cycle, because the translation to IGES will invariably exclude some of the data inherent in the native CAD files. If vector data is not compatible between the user and the source, then the IGES standard should be delivered, as it does allow dissimilar CAD systems to manipulate vector data. Final delivery, however, must be in IGES. CAD2 supports vector data in IGES formats. Project managers should consider acquiring any portion of the drawing package developed from 3-D modelling. Product description data is the most comprehensive form of digital data. Product description data contains all information needed to describe a product completely, and a large portion of this information can be directly interpreted by a computer. Product description data allows the simulation of systems modifications prior to implementation and evaluation of form, fit and function performance of components. In addition, product description data with its inherent intelligence can be used to drive manufacturing processes.

Illustrated Text Data Files

Illustrated text data files provide a dynamic form of source data with two possibilities:

Separated files for text, graphics, alphanumeric, and audio/visual data;
Integrated files consolidating some or all of these different data representations.

Text data files include word processing and desk top publishing applications. Such data files can provide the source data for multiple data applications that allow creation of standard and custom documents as well as manipulation of the data for annotate/excerpt or update/maintain purposes. Text data files can also import generic text [ASCII, SGML, etc.] and graphics [raster, CGM, IGES, etc.] from other sources that may be otherwise incompatible. Also, there are Page Description Languages (PDL), sometimes called text presentation metafiles, which are used to drive output devices such as printers. There may be instances when obtaining text data files involves obtaining more than one format of graphical data. This may be due to multiple graphic sources. This is an acceptable and highly likely situation. The project manager must be aware of this possibility and be prepared to develop/modify the defence system contract requirements accordingly.

Text Formats:

There are three possible text formats available for consideration when invoking the option specifying text data files. They are American Standards Code for Information Interchange (ASCII) and tagged ASCII, Standard Generalized Markup Language (SGML), or raster. They are described below.

ASCII was developed as a method of translation for computer processors to interpret alphanumeric characters and symbols through binary representation. ASCII is the basic text information used by most word processing applications and contains no formatting information other than line feed and/or carriage returns. Word processing applications can import ASCII text from other word processing applications, and some word processing applications can translate formatted ASCII from other word processing applications into their own format. This makes ASCII text ideal for most interim deliverables since it can also be imported into an SGML application where it can be SGML-tagged to become a CALS-compliant deliverable.
SGML is a standard that defines a language for document representation which formalizes markup and frees it of system and processing dependencies. It provides a coherent and unambiguous syntax for describing whatever a user chooses to identify within a document. In the SGML scheme, the document contains only generic tags identifying such structural elements as paragraphs, sections, etc. but no typesetting markup. However, SGML's tagging of ASCII text is a rather cumbersome proposition and may be best suited for final data deliverables rather than interim deliverables. When considering SGML as a deliverable format, the project manager must determine whether the necessary computer environment is available and in place to accept the SGML documentation. Additional features associated with SGML are: Document Type Definition (DTD), Output Specification (OS), Formatting Output Specification Instance (FOSI).

Graphics and Illustration Formats:

There are many possible graphic image formats available for consideration when invoking the option of specifying text data files. Two suggested formats described below are Computer Graphics Metafile (CGM) and raster. CGM data is a two dimensional vector presentation used primarily for charts, figures, and simple drawings. See 3.3.3 for a discussion of raster data.

Standard Page Description Language (SPDL):

A PDL file is executed by an interpreter that controls a raster printer or other output device. A PDL can be used to ensure that the composed document produced by an electronic publishing system (which may impose additional processing limitations, such as font variations, kerning, or hyphenation) would produce nearly identical hardcopy output on the widest possible spectrum of printer devices. SPDL document image files can be acquired as interim deliverables or as final deliverables in addition to (but not in place of) other digital data deliverables.

Neutral Data Files:

Several industry-developed software products for creating platform-independent neutral data files have recently become available that allow users to save information created in a variety of software applications and formats, including text, graphics, and spreadsheets, into a platform-independent file format. These files can then be viewed and printed by anyone possessing the appropriate reader software. Many applications also allow reader-software users to annotate data and copy information to paste into other word processing programmes. Because of their flexibility in handling a wide range of software packages, the NATO/NATO nations may want to consider these platform-independent file applications when determining standard file formats, even though they are not part of the CALS standards.