Prevent Civil 3D from opening LDD files?

[agentORNJ]

We have a mixed environment while we roll out Civil 3D, due to many factors, none of them relevant.  needless to say, currently, our surveyors are working Land Development Desktop 2009, and the engineering staff is working in Civil 3D as AutoCAD 2013.

the problem arises when someone opens a survey file created in LDD with Civil 3D, and saves it.  Obviously, you can then no longer open the file in LDD without first -EXPORTTOAUTOCAD (if you want to use LDD functions, which the surveyors do) and re-reading the database, importing points, etc.

We have the surveys locked down (mostly), but some more experienced users have access.  Occasionally, a drawing gets habitually saved and screws the file for LDD use.

Here's the question.

"Can a LISP be created and loaded each time Civil 3D opens that reads the AutoCAD version the file was saved last in (2007 format), and forces the file to be opened read only?"

Thanks Community. I love you guys.

[Civil3DReminders_com]

It is possible to make a check, but I don't think it can be made to be read-only. It can give an error message to the user and then close the file and tell them to open it readonly. Sorry, I don't have any sample code to do so.