Overview
Portable Document Format (PDF) is a file format developed by Adobe in 1993.
Over time, some of the format and implementations became international standards published by the International Organization for Standardization (ISO).
PDF is probably not going away any time soon. It has benefits, and it has drawbacks, as a practical and economical medium for storing a source of record that is unalterable.
History
PDF currently supports two different methods for integrating data and PDF forms. Both formats today coexist in the PDF specification:
AcroForms (also known as Acrobat forms), introduced in the PDF 1.2 format specification and included in all later PDF specifications. Adobe XML Forms Architecture (XFA) forms, introduced in the PDF 1.5 format specification.
Adobe XFA Forms are not compatible with AcroForms. XFA was deprecated from PDF with PDF 2.0 specification.
PDF Types
PDF documents generally come in two flavors; Acroforms or XFA Forms.
Acroforms:
- The original PDF implementation, PDF based syntax
- Widely support by javascript, implemented by major browsers
XFA (XML Forms Architecture):
- Does not use PDF syntax
- Comes in two different types
- Static XFA - produces a fixed layout of a form
- Dynamic XFA - produces a variable arrange of form fields and a variable number of pages depending on data provided
- Not widely support by PDF viewing application, popular via Adobe authoring tools
Releases
| PDF Version | Release | Summary Release | ISO specification |
|---|---|---|---|
| 1.0 | Nov 1992 | Adobe Acrobat 1.0 | |
| 1.1 | Nov 1994 | Adobe Acrobat 2.0 | |
| 1.2 | Nov 1996 | Support for Acroforms | |
| 1.3 | Apr 1999 | Digital Signature | |
| 1.4 | May 2001 | Adobe Acrobat 5.0 | |
| 1.5 | Apr 2003 | Introduction for XFA | |
| 1.6 | Jan 2005 | XML Forms and enhancement | |
| 1.7 | Oct 2006 | Adobe Acrobat 8.0 | ISO 32000-1 |
| 1.7 Ext Level 3 | 2008 | 256-bit AES encryption | |
| 1.7 Ext Level 5 | 2009 | XFA 3.0 | |
| 2.0 | Aug 2017 | Depreciate XFA | ISO 32000-2 |
Adobe's trends
Adobe is planning on depreciating their LifeCycle Designer and replacing it with Adobe Experience Manager Forms.
Adobe LifeCycle Designer may be used to continue to produce all types of PDFs.
It is also possible to change a Dynamic XFA to a Static XFA according to Google Group thread on LifeCycle.
Static PDF – A PDF which contains an XFA stream and the form layout does not change. Static forms may be interactive (a user can still fill in fields).
If a dynamic XDP is rendered with LiveCycle Forms with the Render At Client option set to “No” then the resulting PDF is no longer dynamic – it is now static and behaves like any other static PDF.
Browser trends
Every major browser has their own version of a built-in PDF viewers.
Major browsers supports Acroforms and not XFA based forms and has disabled the Adobe NPAPI plugin when shipping the browser, causing more headaches in rendering forms.
To major browsers, it was likely removed because Adobe XFA format is a proprietary format that never made it as part of PDF specification, and adding it as part of their browser could have underlying repercussions.
Firefox now includes an embedded PDF viewer with the ability to fill out forms via an open source library known as PDF.js.
References
Moving Forward
Because of the varying degree of support for XFA forms in modern web browsers, makers of PDFs should stay with Acroforms, and keep the forms as simple, and as static as possible.
Acroforms are fillable and are the javascript support for Acroforms (which makes form smart and powerful) are much better than XFA, a depreciated proprietary format in the upcoming PDF specification.
User experience
Solutions
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Make everybody download the PDF, and render it using Adobe Reader (which supports both Acroform and XFA forms).
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Make all the forms Acroforms, instead of XFA based forms. Ensure that all forms are accessible through modern devices.
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Transform form filling into an online form, only generating the PDF after for record storage.