The 10 most important things you should know about PDF/A
PDF/A is a subset of the PDF file format that is designed for long-term preservation of digital documents. Here are the 10 most important things to know about PDF/A.
1. PDF/A is an ISO standard
An ISO standard represents an international consensus for best practice in conforming to a specification or standard. PDF/A has been an ISO standard since October 2005. It was established to meet the specific requirements for long-term archiving. As an open standard, PDF/A is platform and supplier independent. PDF/A builds on established experience in the area of PDF (since 1993).
The format is widely used and established in all industries. The PDF/A standard along with the availability of a large number of viewers (such as Adobe Acrobat/Reader) guarantee the readability of the PDF/A format into the future. The PDF/A standard provides all necessary information to build a PDF/A-compliant viewer, even in many years from now. PDF/A is continuously being enhanced. In 2011 the second part and in 2012 already the third part was published.
2. Standardized metadata is embedded directly into the document
All information used to describe a document (so called “metadata”) is directly embedded in the PDF/A document in a standardized, exchangeable format (XMP, open XML standard). Metadata of other formats such as PNG, PostScript or TIFF can easily be transferred into the PDF/A document. The use of (often proprietary) systems to store such metadata separate from the document is obsolete.
3. PDF/A documents are fully text searchable
The ability to perform full text searches on PDF/A documents is also part of the standard. The text of digitally generated content is preserved in the document. This is also true for scanned documents that have undergone optical character recognition (OCR). The PDF/A file saves both the recognized text (as Unicode) as well as the originally scanned image, which retains the visual appearance yet allows the search function.
4. Everything is included for authentic reproduction
PDF/A files are self-contained: all elements (fonts, color profiles etc.) necessary for a flawless, authentic reproduction are included in the PDF/A file. A PDF/A document may not contain any references to external content or resources. Simple information references like links to web pages are allowed however.
5. PDF/A is space saving
Although PDF/A documents contain more information than images (such as TIFF), the PDF/A files are usually smaller due to the use of efficient compression algorithms.
6. Optimal security with digital signatures
The combination of PDF/A and digital signatures is the perfect way to verify that the PDF document has not been tampered with and that it is also authentic. This provides optimal legal security for long-term archiving.
7. PDF/A can meet accessibility requirements (section 508)
The PDF/A standard contains sub-standards. The ‘Part A’ sub-standards (PDF/A-1a, PDF/A-2a and PDF/A-3a) are the most detailed variants that requires specific information to better assist persons with certain disabilities: for example, text must be stored as Unicode so text-to-speech engines can be supported, and document structure, the reading order as well as descriptions of pictures must be included. Other sub-standards are a less demanding variants, which are sufficient in most cases. Typical application areas are scanned documents and conversions of digital born documents into PDF/A.
8. PDF/A documents remain valid without time limits
The standards committee extends the existing standard every two to four years with meaningful amendments. That does not mean that existing PDF/A documents must be migrated to such new standard amendments. Existing PDF/A documents remain conform perpetually. Contrary to other standards, the ISO cannot withdraw the PDF/A standard.
9. PDF/A being widely accepted
In Europe and Asia, PDF/A is already recommended or required and legislated for long-term archiving in several governments, organizations and corporations. Also in North America such recommendations exist in the areas of jurisdiction and libraries and the demand for this standard is growing continuously. The PDF Association (see next page) is instrumental in supporting the PDF/A standard.
10. Reliable tools are available today
Thanks to the long experience with PDF and the fast response of the major PDF technology suppliers, there are already many PDF/A compliant software tools on the market. The PDF Association has developed a test suite that allows PDF/A validation software products to be validated reliably. A validator helps to check whether a document conforms to the PDF/A standard or not.
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