XSLfast ships the Renderer FOP with the application. FOP offers enough functionality to produce professional and good looking documents but also has limitations to its function range. We refrain from listing all the limitations here because it would be impossible to track all the changes made in FOP to keep this list up to date in reasonable intervals. Also there is a lot of superb information like comparisons between different Renderers available in the Internet, which provide all information on limitations of Renderers that you will need.