Of the order and location of graphics objects on the document's pages. The ordering and nesting of logical elements to be entirely independent In PDF, renderedĭocument content takes over the role occupied by text in HTML, SGML,Ī PDF document's logical structure is stored separately from its visibleĬontent, with pointers from each to the other. PDF structure elements can have content and attributes. Like their counterparts in other markup languages, Structure is expressed as a hierarchy of structure elements, each representedīy a dictionary object. Markup languages such as HTML, SGML, and XML. PDF logical structure shares basic features with standard document Information to include and how to represent it, while enabling PDFĬonsumers to navigate a file without knowing the producer's structural The logical structure features are extensible,Īllowing applications that produce PDF files to choose what structural The organization of the document into chapters, headings, paragraphsĪnd sections or the identification of special elements such as figures, Such information might include, for example, Mechanism for incorporating structural information about a document'sĬontent into a PDF file. PDF's logical structure features (introduced in PDF 1.3) provide a PDF/UA also specifies the rules governing the behavior for a conforming reader. The mechanisms for including the components in the PDF stream are left to the discretion of the individual developer, PDF generator, or PDF viewing agent.
The specification describes the required and prohibited components and the conditions governing their inclusion in or exclusion from a PDF file in order for the file to be available to the widest possible audience, including those with disabilities. Wiki (ISO DIS 14289 - 1).) The scope of PDF/UA is not meant to be a techniques (how-to) specification, but rather a set of guidelines for creating more accessible PDF. Of note for accessibility is PDF/UA (Universal Accessibility) which became an ISO Draft International Standard (DIS) in November 2010 (ISO/DIS 14289-1(See PDF/UA In January 2008, PDF 1.7 became an ISO standard (ISO 32000-1). The PDF specification was introduced by Adobe Systems in 1993 as a publicly available standard. PDF files specify the appearance of pages in a document in a reliable, device-independent manner. The Portable Document Format (PDF) is a file format for representing documents in a manner independent of the application software, hardware, and operating system used to create them, as well as of the output device on which they are to be displayed or printed.
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