Apoc XSL-FO by Chive Software is the first commercially available XSL-FO document renderer for the Microsoft .NET platform. Apoc XSL-FO is a .NET component, written in 100% managed code, that renders XSL-FO XML documents directly to PDF. Based on the excellent Apache FOP project, Apoc will add standards-based PDF production to any .NET project.

http://www.chive.com/products/apoc/

What is XSL-FO?
Extensible Stylesheet Language - Formatting Objects (XSL-FO) is defined as part of the World Wide Web consortium's (W3C) specification for XSL. The XSL specification also defines a language for transforming XML documents called XSLT. This article will deal solely with the XSL-FO aspect of the XSL specification.

XSL-FO is an XML markup language for describing the layout, pagination and styling of a document. The specification is extensive, providing an array of Formatting Objects and Properties that permit a document designer to describe a document's visual characteristics down to the finest detail.

Creating an XSL-FO document by hand would be extremely time consuming simply because the specification is so verbose. Therefore, the production of an XSL-FO document is normally handled by applying a XSLT stylesheet to an XML document.

The XSLT stylesheet matches certain element and/or attributes within an XML document producing a series of XSL-FO elements.