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The File Extension Library

What is a file extension?

Short answer: it's the set of letters after the period (.) in the name of a file.

Long answer: File extensions signify the file format of a file. It tells the operating system (OS) how data was stored in the file. Not all OS, require a file extension though. For instance, this is optional in Unix, but is mandatory with MS-DOS and Windows systems.

In most file formats the file type is actually defined by the contents (first bytes, file structure), but extensions are used to define the application that is used for opening the file.

Below is a detailed database of thousands of file extensions our team has compiled for you. Feel free to browse!


Browse all Extensions:
ABCDEFGHIJKLMNOPQRSTUVWXYZ
XFDL - Extension Details
Date Added: April 09, 2008
File Extension:  .XFDL
Description 1: XFDL is short for Extensible Forms Description Language. It is a type of XML (Extensible Markup Language) that is specified in the W3C (World Wide Web Consortium). The .XFDL file extension is a highlevel computer language facilitating the definition of a form as a standalone, single object using the various XML attributes and elements. As an XML extension language, XFDL is able to address key issues concerning the conduct of online electronic commerce.
File Type:   Text file
Mode: ASCII
Program(s) to Open:  Mac, Windows and Unix: Any text editor
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