FYI, the Print and Page Layout Community Group @ W3C , as part of a focus on getting more feedback in XSL-FO processing, has developed extension functions for Xalan, Saxon 9.5, and the DotNet XSLT processors for running FOP and getting back an area tree .
The wiki page at https://www.w3.org/community/ppl/wiki/XSLTExtensions shows some examples of why you'd use such an extension. The extension functions are available under the open source W3C license (as you might expect). The code is available from the CG's Hg repository , and a (fairly) up-to-date copy of the source can be downloaded from the wiki page. Any comments on or improvements to the code would be welcome. E.g., the extension function for running Antenna House on DotNet has an optional parameter for a config file, but we don't have that for FOP with any of the XSLT processors. Regards, Tony Graham tgra...@mentea.net Consultant http://www.mentea.net Chair, Print and Page Layout Community Group @ W3C XML Guild member -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Mentea XML, XSL-FO and XSLT consulting, training and programming  http://www.w3.org/community/ppl/  https://dvcs.w3.org/hg/ppl  As well as for running Antenna House, but that's likely to be of less interest to people here.