.FO file extension

This is the basic program to work with .FO extension

Altova XMLSpy

Altova XMLSpy Formatting Objects

Altova XMLSpy is the industry’s best-selling XML editor and XML development environment for modeling, editing, transforming, and debugging XML technologies. In addition to the world’s leading XML editor, XMLSpy includes a powerful graphical XML Schema editor that allows you to design complex schemas with ease... (more)

The program works with the following extensions: xml, fo, xq, biz, tsd, mtx, tld, jsp, cml, dcd, ent, xsl, rdf, spp, svg, mml, vml, dtd, wml, xdr, xsd, xql, xslt, rels, math, smil, vxml, wsdl, xhtml and xquery

.FO extension is also supported by the following programs:

Oxygen XML Editor

Oxygen XML Editor XSL-FO Document

Edit, convert, and debug XML databases, files, and servers.
AH Formatter

AH Formatter AH Formatting Objects

AH Formatter is an app for format HTML and XML files for print.
602XML Filler

602XML Filler 602XML Form