Posted by Rallaz on Mar 18, 2013; 9:23am
URL: https://forum.librecad.org/LibreCAD-DXF-File-Structure-tp5707695p5707717.html

Hi Avneet Kaur,

LibreCAD 1.x.x uses the old dxflib, only writes R12 & 2000 and do not support polyline contour

LibreCAD 2.x.x uses the new libdxfrw and writes in R12, 2000, 2004 & 2007.

You can found libdxfrw source code in:
https://github.com/LibreCAD/LibreCAD/tree/master/libraries/libdxfrw

Or if you want to work with it outside LC get it from:
http://sourceforge.net/projects/libdxfrw/
Is the same source code with standard ./comfigure & make & make install

Versions are documented in lines #45 to #54:
https://github.com/LibreCAD/LibreCAD/blob/master/libraries/libdxfrw/src/drw_base.h

Since you use ubuntu you can update your installation to daily builds