XML format changes continuously as we add new features, however it remains
compatible. We guarantee that it remains the same across minor updates, we
guarantee that older files are readable by newer GanttProject versions and
we do our best to make sure that newer files are at least partially
readable by older GanttProject versions.
With respect to reporting, we plan integration with Jasper Reports with
slightly different format (JSON) as data source. It will be covered by the
same guarantees when released.