Save to R12 DXF, Custom objects not compatible, but what are they?????

I'm saving a drawing as R12 dxf to put into another bit of software (S-Paramics) as the mapping for a traffic model. When I save to dxf it says "This drawing contains custom objects that are not supported in previous versions....". It saves it, but I put it into Paramics and it looks weird.

How do I find out what these custom objects are so I can delete them or convert them?

Thanks

Those custom objects could be things like MTEXT for example that did not exist back when Release 12 was around.

By any chance was the drawing edited with an AutoCAD vertical product such as Map or Civil 3D?

I couldnt tell you that as its a drawing received from a client. Is there a way to save it but make it remove all the things that arent compatible? or does it do that automatically?

Can you ask the client what part was used?

Try this command first and see what happens: AECOBJEXPLODE. Use a copy of the drawing not the original.

it says 'unknown command' when i type that, there's one called AECFORCEEXPLODETOSOLID though?

No, that won't do. AutoCAD 2013? Let me check something. I'll be back.

Hmmmm.....guess I was wrong.

OK. Can you attach a copy of the drawing to your next post?

In the meantime, call the client and find out what program was used.