It's the "AutoCAD Drawing Interchange Format", which is basically a text file with all the objects on the screen. A simple dxf file that draws a line from (1,2) to (3,4) would be:
Text and lines are easy. Filled areas could be represented by wireframes or lines. A page about dxf files is at:
Basically, all the info is in the structured file ppreview already outputs. If I have time one day I'll try to write some code that extracts some of the things out of the structured file.
What are the various types of elements in the structured file? I quickly see that type 3 is some kind of text, 14 is a roundrect(?), etc. Any chance of getting a list of these?