I'm currently developing a solution that utilizes Open Design Alliance to read DWG files. I'm trying to implement a similar feature that exists in the AutoCad program itself -- AutoCad will notify the user if the file's origin is not from a licensed AutoCad application. (See Here)
I have explored the library in depth and have concluded that the information I need to determine this is most likely available but I'm having a hard time figuring out what the guidelines are that signify the file is from AutoCad origin, or not. Any Ideas?