Posted by Rallaz on Mar 15, 2013; 8:00pm
URL: https://forum.librecad.org/LibreCAD-DXF-File-Structure-tp5707695p5707696.html

Avneet wrote

...it missed classes section.
Why it is not including this section??
Is it not need to include??

 In short: No.

More long:

DXF R12 do not have CLASSES, OBJECTS AND Thumbnailimage

The first version wiht CLASSES & OBJECTS is R13 and Thumbnailimage exist since v2000

And you forgot the BLOCK section between TABLES and ENTITIES.

Thumbnailimage section from dxf doc:
"This section exists only if a preview image has been saved with the DXF file."

And CLASSES section:
"holds the information for application-defined classes" (proxy graphics p.e.)

The only mandatory section is ENTITIES like the attached and valid dxf v2007:
minimal.dxf