Open Document Architecture

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The Open Document Architecture (or sometimes referred to as Office Document Architecture or just ODA) is a standard document file format maintained by the ITU-T to replace all proprietary document file formats. It should not be confused with the OASIS Open Document Format for Office Applications, also known as OpenDocument.

ODA is detailed in the standards documents CCITT T.411-T.424, which is equivalent to ISO 8613. The Standard was initially completed at a ISO working group meeting in Ottawa in February 1989 and was first approved for release in that year. Improvements and additions were continually being made. The revised standard was finally published in 1999.

ODA defines a compound document format that can contain raw text, raster images and vector graphics. In the original release the difference between this standard and others like it is that the graphics structures were exclusively defined as CCITT raster image and Computer Graphics Metafile (CGM - ISO 8632). This was to limit the problem of having word processor and desk top publisher software be required to interpret all known graphics formats.

The documents have both logical and layout structures. Logically the text can be partitioned into chapters, footnotes and other subelements akin to HTML, and the layout fill a function similar to Cascading Style Sheets in the web world. The binary transport format for an ODA-conformant file is called Open Document Interchange Format (ODIF) and is based on the Standard Generalized Markup Language and Abstract Syntax Notation One (ASN.1).

One of the features of this standard was that the documents could be stored or interchanged in one of three formats: Formatted, Formatted Processable, or Processable. The latter two are editable formats. The first is an uneditable format that is logically similar to Adobe PDF that is in common use today.

The intent was to have a universal storable and interchangeable document structure that would not go out of date and could be used by any word processor or desk top publisher. This was to solve the problem of the software applications that had their native file formats continually updated, sometimes rendering older native formats obsolete and therefor unusable. There was a large financial impact on companies that used ad hoc standard applications, such as MS Word or Word Perfect, because of the need to maintain groups of people whose sole job was to import old stored documents into the latest version of the application before it became unreadable. The intended result of this standard was that companies need not commit to an ad hoc standard for word processor or desk top publisher applications, because any could be used to read and edit long stored documents.

In 1985 ESPRIT financed a pilot implementation of the ODA concept, involving, among others, Bull corporation, Olivetti, ICL and Siemens AG. However, no significant developer of document software chose to support the format. It also took an extraordinarily long time to release the format (the pilot was financed in 1985, but the final specification not published until 1999). Given a lack of products that supported the format, in part because of the excessive time used to create the specification, few users were interested in using it. Eventually interest in the format faded.

It would be improper to call the ODA anything but a failure, but its spirit clearly influenced latter-day document formats that were successful in gaining support from many document software developers and users. These include the mentioned HTML and CSS as well as XML and XSL leading up to OpenDocument.

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The standard itself was made available for free download on September 7, 2007 (the "missing" documents T.420 and T.423 do not exist):

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