Topic Title

How can I open the file *AEC thet creat at V.11 by V.10 ?

Thanks.

The file is automatically and permanently changed when you go from v10 to v11. If you REALLY need to go back to v10 (I can't imagine why you would want to do that), you will have to chose file/export and export the file as a dxf or a dwg file. Then you can go open your v10 DataCAD and create a new .dc5 drawing and import the .dxf or .dwg file that you exported. Some features may be lost, but that's about the easiest way to do it.

If I understand your question, you cannot open an AEC file in v10. You can convert it to a dxf (file|export|dxf) or a dwg, and then bring it into V10.

Versions prior to 11 use a different file format, its not backward compatible.