In order to ensure future access to PDF documents for as many people as possible, the ISO standard (known as PDF/UA) was developed by specialists. Mar 19, The PDF has developed through many different versions and subsets over the course of almost three decades and became ISO standard in the. Sep 27, By , PDF had become an official global standard after incorporation into the International Organization for Standardization (ISO).
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Jul 2, The Portable Document Format (PDF), undeniably one of the most commonly used formats for electronic documents, is now accessible as an. The Portable Document Format (PDF) is a file format developed by Adobe in the s to PDF was standardized as an open format, ISO , in , and no .. Alongside the standard PDF action types, interactive forms (AcroForms). PDF/A is an ISO-standardized version of the Portable Document Format (PDF) specialized for . Part 2 of the PDF/A Standard is based on a PDF (ISO ), rather than PDF and offers a number of new features: JPEG image.
It was published in UA means "Universal Accessibility". It deals with the unrestricted access to documents in PDF format for persons with disabilities. The aim is to create guidelines that define how PDF documents and the content they contain, like graphics, text, multimedia elements and form fields, have to be depicted in order that they are accessible to persons with disabilities.
The working group at AIIM is currently not fully active and therefore a publication date for the standard cannot be established. Do you have questions? PDF 1. Further information about PDF. PDF 1.
Some of the additions feature-wise were allowing users to use PDF as an electronic form, extending character sets, color, and interactive elements support.
The model is closely aligned with the features of Adobe Illustrator version 9. The blend modes were based on those used by Adobe Photoshop at the time. When the PDF 1. They have since been published. The concept of a transparency group in PDF specification is independent of existing notions of "group" or "layer" in applications such as Adobe Illustrator.
Those groupings reflect logical relationships among objects that are meaningful when editing those objects, but they are not part of the imaging model.
PDF files may contain interactive elements such as annotations, form fields, video, 3D and rich media. Both formats today coexist in PDF specification: AcroForms were introduced in the PDF 1.
AcroForms permit using objects e. Alongside the standard PDF action types, interactive forms AcroForms support submitting, resetting, and importing data. The "submit" action transmits the names and values of selected interactive form fields to a specified uniform resource locator URL.
AcroForms can keep form field values in external stand-alone files containing key: The Forms Data Format can be used when submitting form data to a server, receiving the response, and incorporating into the interactive form. It can also be used to export form data to stand-alone files that can be imported back into the corresponding PDF interactive form.
In addition, XFDF does not allow the spawning, or addition, of new pages based on the given data; as can be done when using an FDF file. A "tagged" PDF see clause Technically speaking, tagged PDF is a stylized use of the format that builds on the logical structure framework introduced in PDF 1.
Tagged PDF defines a set of standard structure types and attributes that allow page content text, graphics, and images to be extracted and reused for other purposes.
With the introduction of PDF version, 1. Layers, or as they are more formally known Optional Content Groups OCGs , refer to sections of content in a PDF document that can be selectively viewed or hidden by document authors or consumers. This capability is useful in CAD drawings, layered artwork, maps, multi-language documents etc. Basically, it consists of an Optional Content Properties Dictionary added to the document root. This dictionary contains an array of Optional Content Groups OCGs , each describing a set of information and each of which may be individually displayed or suppressed, plus a set of Optional Content Configuration Dictionaries, which give the status Displayed or Suppressed of the given OCGs.
A PDF file may be encrypted for security, or digitally signed for authentication. The standard security provided by Acrobat PDF consists of two different methods and two different passwords: The user password encrypts the file, while the owner password does not, instead relying on client software to respect these restrictions. An owner password can easily be removed by software, including some free online services. Even without removing the password, most freeware or open source PDF readers ignore the permission "protections" and allow the user to print or make copy of excerpts of the text as if the document were not limited by password protection.
There are a number of commercial solutions that offer more robust means of information rights management. Not only can they restrict document access but they also reliably enforce permissions in ways that the standard security handler does not. The signature is used to validate that the permissions have been granted by a bona fide granting authority. For example, it can be used to allow a user: For example, Adobe Systems grants permissions to enable additional features in Adobe Reader, using public-key cryptography.
Adobe Reader verifies that the signature uses a certificate from an Adobe-authorized certificate authority. Any PDF application can use this same mechanism for its own purposes. PDF files can have file attachments which processors may access and open or save to a local filesystem. PDF files can contain two types of metadata. This is stored in the optional Info trailer of the file.
A small set of fields is defined, and can be extended with additional text values if required. This method is deprecated in PDF 2.
This allows metadata to be attached to any stream in the document, such as information about embedded illustrations, as well as the whole document attaching to the document catalog , using an extensible schema. PDFs may be encrypted so that a password is needed to view or edit the contents. PDF 2. PDF files may also contain embedded DRM restrictions that provide further controls that limit copying, editing or printing. These restrictions depend on the reader software to obey them, so the security they provide is limited.
PDF documents can contain display settings, including the page display layout and zoom level. Adobe Reader uses these settings to override the user's default settings when opening the document.
Anyone may create applications that can read and write PDF files without having to pay royalties to Adobe Systems ; Adobe holds patents to PDF, but licenses them for royalty-free use in developing software complying with its PDF specification.
PDF files can be created specifically to be accessible for disabled people. Some software can automatically produce tagged PDFs, but this feature is not always enabled by default. Adding tags to older PDFs and those that are generated from scanned documents can present some challenges. One of the significant challenges with PDF accessibility is that PDF documents have three distinct views, which, depending on the document's creation, can be inconsistent with each other.
The three views are i the physical view, ii the tags view, and iii the content view. The physical view is displayed and printed what most people consider a PDF document. The tags view is what screen readers and other assistive technologies use to deliver a high-quality navigation and reading experience to users with disabilities.
The content view is based on the physical order of objects within the PDF's content stream and may be displayed by software that does not fully support the tags view, such as the Reflow feature in Adobe's Reader.
PDF attachments carrying viruses were first discovered in It was activated with Adobe Acrobat, but not with Acrobat Reader.
From time to time, new vulnerabilities are discovered in various versions of Adobe Reader,  prompting the company to issue security fixes. Other PDF readers are also susceptible. One aggravating factor is that a PDF reader can be configured to start automatically if a web page has an embedded PDF file, providing a vector for attack.