[LibreCAD ​https://librecad.org/] is a nice open-source alternative to e.g. !AutoCAD for simple 2D drawing. It's native format is DXF, which is supposed to be interchangeable with !AutoCAD. However, as of now (LibreCAD 2.1.3) the DXF files produced provoke an error in at least !AutoCAD2000 such as:

  Unknown group 49 for table on line xxxx
  Invalid or incomplete DXF input -- drawing discarded

See ​DXF format info (or ​local copy).

The troublesome entity is a table which begins:

  0
TABLE
  2
DIMSTYLE

and ends:

  0
ENDTAB

After a few tests it seems that deleting this table makes the file usable. Writing a perl script...