QUESTION: What's the difference between FDF and XFDF?

ANSWER:  FDF and XFDF are both file formats for representing the form data and annotations that are contained in a PDF form. There are two main differences between FDF format and XFDF format:

  1. The syntax used for representing information in FDF format is different than the syntax used for representing that same information in XFDF format.

  2. There are some kinds of information that can be represented in FDF format but cannot be represented in XFDF format. Specifically: the following information in a PDF form can be represented in FDF format but not in XFDF format: Status, Encoding, JavaScript, EmbeddedFDFs, Differences, Target, and Pages.

This is what FDF looks like

FDF stands for "Forms Data Format." In the FDF format, information is represented in the form of key/value pairs. Here is an example of some FDF code that represents a form field named Street with a value of 345 Park Avenue.

/T(Street)/V(345 Park Avenue)

In this example, there are two keys and two values: a key named T with a value of Street, and a key named V with a value of 345 Park Avenue.

This is what XFDF looks like

XFDF stands for "XML Forms Data Format" — so, as you would expect, XML syntax is used. Here is XFDF code that represents the information above.

<field name="Street">
<value>345 Park Avenue</value>

More information

For more information about the FDF format, click here.
For more information about the XFDF format, click here.