We recently did a project in AutoCAD P&ID 2013 and sent electronic files to our client. I did an Export to AutoCAD as AutoCAD 2010 (using the option in the right-click menu in Project Manager) assuming that this would create a file that would be able to be opened by our client in AutoCAD 2010. The client was unable to open these files and the error implied that the files were saved as a newer version of AutoCAD. I re-saved them as AutoCAD 2000 and they were able to open them just fine. I’m afraid I don’t understand why. If AutoCAD P&ID 2013 has a different drawing file format, then why does the Files of Type list 2007 and 2010 as the saved file format options when it is clearly a 2013 format file?
Confirmed this is a bug. Clearly autodesk forgot to update this function. (they should provide three selection now 2007, 2010 and 2013) Selecting 2007 will works but selecting 2010 will default to 2013 version.
The suggestion Rav.Tam made was correct. When saving down from 2013 to be able to use on 2010, you would have to save it as 2007 instead. Please refer to this link for more information concerning the saving format changes.