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+The core directory for the impress/draw applications.
+
+Think of impress as a hack on top of draw.
+
+
+sd module contains impress/draw specific code, non-shared UI and part
+of ppt and pptx filter, few other filters too.
+
+the slideshow UI lives here as well, the slideshow engine is in
+slideshow module though (including the 3D transitions engine
+slideshow/source/engine/opengl).
+
+the most used filters are ODF's odp, binary ppt and OOXML's
+pptx. their locations are listed below:
+
+ * odp import and export filters are in xmloff module (mostly xmloff/source/draw)
+
+ * ppt import is in sd/source/filter/ppt (big shared chunks are also in svx)
+ * ppt export is in sd/source/filter/eppt (big shared chunks are also in svx)
+
+ * pptx import is in oox/source/ppt (and uses a lot of
+   oox/source/drawingml and oox/source/*)
+ * pptx export is in sd/source/filter/eppt (mostly in pptx-* source
+   files) and shared part is in oox/source/export
+
+== PPTX export/import filters ==
+
+PPTX export filter is split into 2 parts. Impress related part is in
+sd/source/filter/eppt/pptx-* and the other part is in
+oox/source/export/ because it contains mostly code related to
+DrawingML, which is shared with writer and calc ooxml export.
+
+The export filter was written in 2009 IIRC and was not much extended
+feature-wise lately.
+
+FUTURE work: add custom shapes export (see below). enhance text
+output, we don't write text style for indentation levels now, need to
+export a:lvl1pPr, a:lvl2pPr, ... elements.
+
+PPTX import was written by Sun/Oracle and then extended in LibreOffice
+a lot during bug fixing. It is located in oox/source/ppt and
+oox/source/drawingml. The areas with most bugs (at least until today)
+were shape placeholders and text style inheritance.