What is FO? FO, short name for Formatting Objects, is used as the file extension for XSL-FO files. .FO files are XML files that can be opened by Notepad or any text editors. See the sample .FO file included below.

File Extension: .FO

MIME Type: text/xml

File Content: XSL-FO

.FO files are XSL-FO files, which contain formatted objects for printing in XML format. Here is a sample .FO XSL-FO file, helloworld.fo, with a simple formatted text object:

<?xml version="1.0" encoding="UTF-8"?>
<fo:root xmlns:fo="http://www.w3.org/1999/XSL/Format">
  <fo:layout-master-set>
    <fo:simple-page-master master-name="simpleA4" page-height="29.7cm" 
      page-width="21cm" margin-top="2cm" margin-bottom="2cm" 
      margin-left="2cm" margin-right="2cm">
      <fo:region-body/>
    </fo:simple-page-master>
  </fo:layout-master-set>
  <fo:page-sequence master-reference="simpleA4">
    <fo:flow flow-name="xsl-region-body">
      <fo:block>Hello World!</fo:block>
    </fo:flow>
  </fo:page-sequence>
</fo:root>

.FO XSL-FO file sample: Click sample.fo to download.

Since .FO text files are in text format, you can use Notepad or any text editor to create or modify them. No special software is needed.

For for information on how to use .FO XSL-FO files, see links below:

• Introduction to XSL-FO