XSL-FO is a primary input format for XML2PDF Formatting Engine. Originally, XSL-FO stylesheets are used to express designer’s intentions about how that structured content of a class of arbitrarily structured XML documents or data files should be presented. That is, how the source content should be styled, laid out, and paginated onto some presentation medium (PDF in this particular case).
The current implementation provides nearly the complete level of conformance for “Extensible Stylesheet Language (XSL) version 1.1 W3C Recommendation” dated 05 December 2006 including bookmarks, multiple flows, and floats.
Both XML parser and XSL-FO formatter are designed to be user friendly and error resistant. Thus, even if small errors or warnings exist the file will be formatted and all warnings will be reported to the user. XML2PDF Formatting Engine tries also to produce as much informative output as possible if more serious errors occur.
There are several configuration properties that have an impact on the formatting process, such as font usage policy, maximal image resolution, a number of default values, etc. See user manual of the edition you are interested in for the particular details.
Altsoft provides a number of extension to XSL-FO in order to cover the special requirements of the real projects that are missing in the specification. These are layers in PDF, attachments in PDF file and document properties (autor name, subject, keywords, etc). Please, refer to the complete list of extensions to XSL-FO by Altsoft.