Level A conformance was intended to increase the accessibility of conforming files for physically impaired users by allowing assistive software, such as screen readers, to more precisely extract and interpret a file's contents. ![]() Tagged text spans and descriptive text for images and symbols.Level B conformance requires only that standards necessary for the reliable reproduction of a document's visual appearance be followed, while Level A conformance includes all Level B requirements in addition to features intended to improve a document's accessibility. PDF/A-1a – Level A (accessible) conformance.Part 1 of the standard was first published on September 28, 2005, and specifies two levels of conformance for PDF files: The appearance dictionary shall be used when rendering the field.Ĭonformance levels and versions PDF/A-1 Interactive PDF form fields must have an appearance dictionary associated with the field's data.(XFA form data may be preserved in a PDF/A-2 file by moving from XFA key to the Names tree that itself is the value of the XFAResources key of the Names dictionary of the document catalog dictionary.) The use of XML-based XML Forms Architecture (XFA) forms is forbidden in PDF/A.PDF/A-3 allows embedding of any file format such as XML, CAD and others into PDF/A documents. Embedded files are forbidden in PDF/A-1, but PDF/A-2 allows embedding of PDF/A files, facilitating the archiving of sets of PDF/A documents in a single file.Provisions for digital signatures in accordance with the PAdES (PDF advanced electronic signatures) standard are supported in PDF/A-2.Transparent objects and layers (Optional Content Groups) are forbidden in PDF/A-1 but are allowed in PDF/A-2.JPEG 2000 compression is allowed in PDF/A-2 and PDF/A-3. JPEG 2000 image compression models are not allowed in PDF/A-1 (based on PDF 1.4), as it was first introduced in PDF 1.5. LZW is forbidden due to intellectual property constraints.External content references are forbidden.Use of standards-based metadata is required.Colorspaces specified in a device-independent manner.This also applies to the so-called PostScript standard fonts such as Times or Helvetica. All fonts must be embedded and also must be legally embeddable for unlimited, universal rendering.JavaScript and executable file launches are forbidden.Other key elements to PDF/A conformance include: hypertext links) that link to external documents. font programs and data streams), but may include annotations (e.g. A PDF/A document is not permitted to be reliant on information from external sources (e.g. This includes, but is not limited to, all content (text, raster images and vector graphics), fonts, and color information. All of the information necessary for displaying the document in the same manner is embedded in the file. A key element to this reproducibility is the requirement for PDF/A documents to be 100% self-contained. ![]() It identifies a "profile" for electronic documents that ensures the documents can be reproduced exactly the same way using various software in years to come. The PDF/A standard does not define an archiving strategy or the goals of an archiving system. This need exists in a wide variety of government, industry and academic areas worldwide, including legal systems, libraries, newspapers, and regulated industries. The goal was to address the growing need to electronically archive documents in a way that would ensure preservation of their contents over an extended period of time and ensure that those documents would be able to be retrieved and rendered with a consistent and predictable result in the future. ![]() PDF/A was originally a new joint activity between the Association for Suppliers of Printing, Publishing and Converting Technologies ( NPES) and the Association for Information and Image Management AIIM in conjunction with Adobe to develop an international standard defining the use of the Portable Document Format (PDF) for archiving documents. However, the suitability of a PDF file for archival preservation depends on options chosen when the PDF is created: most notably, whether to embed the necessary fonts for rendering the document whether to use encryption and whether to preserve additional information from the original document beyond what is needed to print it. PDF is a standard for encoding documents in an "as printed" form that is portable between systems. Part 3: Use of ISO 32000-1 with support for embedded files ![]() PDF 1.4 ( Adobe Systems, PDF Reference, third edition) Standards ISO 19005 – Document management – Electronic document file format for long-term preservation (PDF/A)
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