XFA (also known as XFA forms) stands for XML Forms Architecture, a family of proprietary XML specifications that was suggested and developed by JetForm to enhance the processing of web forms. It can be also used in PDF files starting with PDF 1.5 specification. XML Forms Architecture was not standardized as an ISO standard.
XFA's main extension to XML are computationally active tags. In addition, all instances created from a given XFA form template keep the specification of data capture, rendering, and manipulation rules from the original. Another major advantage of XFA is that its data format allows compatibility with other systems, and with changes to other technology, applications and technology standards.
According to JetForm's submission to the World Wide Web Consortium, "XFA addresses the needs of organizations to securely capture, present, move, process, output and print information associated with electronic forms." The XFA proposal was submitted to the W3C in May 1999.
XFA forms are saved internally in PDF files or as XDP (XML Data Package) files which can be opened in Adobe's LiveCycle Designer software. An XDP packages a PDF file, along with XML form and template data. XDP provides a mechanism for packaging form components within a surrounding XML container.
XFA forms are synonymous with SmartForms in the Australian government.
Usage with Portable Document Format 
- AcroForms (also known as Acrobat forms), introduced and included in the PDF 1.2 format specification.
- Adobe XML Forms Architecture (XFA) forms, introduced in the PDF 1.5 format specification as an optional feature (The XFA specification is not included in the PDF specification, it is only referenced.)
Adobe XFA Forms are not compatible with AcroForms. Creating XFA Forms for use in Adobe Reader requires Adobe LiveCycle Forms Designer. Adobe Reader contains "disabled features" for use of XFA Forms, that will activate only when opening a PDF document that was created using enabling technology available only from Adobe. The XFA Forms are not compatible with Adobe Reader prior to version 6.
XFA forms can be created and used as PDF files or as XDP (XML Data Package). The format of an XFA resource in PDF is described by the XML Data Package Specification. PDF may contain XFA in XDP format, but also XFA may contain PDF.
When the PDF and XFA are combined, the result is a form in which each page of the XFA form overlays a PDF background. This architecture is sometimes referred to as XFAF (XFA Foreground). The alternative is to express all of the form, including boilerplate, directly in XFA (without PDF). It is sometimes called full XFA.
When the XFA (XML Forms Architecture) grammars used for an XFA form are moved from one application to another, they must be packaged as an XML Data Package. The XDP may be a standalone document or it may in turn be carried inside a PDF document.
Starting with PDF 1.5, the text contents of variable text form fields, as well as markup annotations may include formatting information (style information). These rich text strings are XML documents that conform to the rich text conventions specified for the XML Forms Architecture specification, which is itself a subset of the XHTML 1.0 specification, augmented with a restricted set of CSS2 style attributes. In PDF 1.6, PDF supports the rich text elements and attributes specified in the XML Forms Architecture (XFA) Specification, 2.2. In PDF 1.7, PDF supports the rich text elements and attributes specified in the XML Forms Architecture (XFA) Specification, 2.4. PDF 2.0 (ISO 32000 Part 2) will reference XFA 3.1.
The XML Forms Architecture specification is not included in the PDF 1.7 standard (ISO 32000-1:2008) and it is only referenced as an external proprietary specification created by Adobe. XFA was not standardized as an ISO standard.
Since 2007, development of PDF standard is conducted by ISO's Technical Committee 171/Subcommittee 2/Working Group 8 (TC 171/SC 2/WG 8) formally named PDF specification.
In 2011 the ISO Committee urged Adobe Systems to submit the XFA Specification, XML Forms Architecture (XFA), to ISO for standardization and requested Adobe Systems to stabilize the XFA specification. The Committee expressed its concerns about the stability of the XFA specification.
See also 
- "Gnu PDF - PDF Knowledge - Forms Data Format". Retrieved 2010-02-19. "Apparently Adobe introduced something newer called XFA (XML Forms Architecture) which doesn't seem standardized."
- W3C Submission (accessed August 14, 2006)
- A Quick Introduction to Acrobat Forms Technology (PDF format)
- Adobe Systems Incorporated. "Adobe XML Forms Architecture (XFA)". Retrieved 2010-02-19.
- "About PDF forms". Retrieved 2010-02-19.
- "Adobe LiveCycle Reader Extensions ES2". Retrieved 2010-02-19.
- Adobe Reader - Software license agreement (PDF), retrieved 2010-02-19
- "LiveCycle Reader Extensions ES features and benefits". Retrieved 2010-02-19.
- Adobe Systems Incorporated (2008-07-01), Document Management – Portable Document Format – Part 1: PDF 1.7, First Edition, retrieved 2010-02-19
- XML Forms Architecture (XFA) Specification Version 2.5 (PDF), 2007-06-08, retrieved 2010-02-19
- ISO/TC 171/SC 2/WG 8 N 603 - Meeting Report, 2011-06-27, "XFA is not to be ISO standard just yet. ... The Committee urges Adobe Systems to submit the XFA Specification, XML Forms Architecture (XFA), to ISO for standardization ... The Committee is concerned about the stability of the XFA specification ... Part 2 will reference XFA 3.1"