Posted by marcin on Jun 15, 2022; 6:06am
URL: https://forum.librecad.org/Double-lines-and-unwanted-connections-tp5721810p5721815.html

LordOfBikes,

The DXF is really old. AC1009 is DXF R11/R12 format and thus pre 1995!

I decided to investigate this a bit more. According to https://www.loc.gov/preservation/digital/formats/fdd/fdd000446.shtml  AC1009 has been published together with  AutoCAD Release 11 which, according to https://autodesk.blogs.com/between_the_lines/autocad-release-history.html has been released 1990. So yes, it is ancient.

It lacks many information, like variables and tables.

 Does this mean, it is broken or invalid?

 your DXF contains special polylines. It needed some investigation to figure this out.

I am new to dxf and curious how you went about investigating this issue. So if you cared to leave some hints or directions on what steps you have taken here I'd appreciate that a lot. :-)

In fact I've never seen this before, it must be a rarely used feature. And it is not implemented in LibreCAD.

The orogin of this dxf file is a big commercial cad software package which is very popular within the engineering industry. Therefore I'd expect this kind of issues to come up more often in the future. So I feel it is even more important to let LibreCad issue a warning when it encounters this kind of old cruft. Pointing blame in the right direction should help reduce frustration and support requests in the LibreCad forum.


Anyway, thanks a lot for your support.