Drawing (DWG) files are used to store blocks and 2D/3D designs that you create with the AutoCAD-based product.
There are some changes to AutoCAD 2016-based products that will affect your drawing files. The changes that might affect your drawing files are:
If your existing drawing files don't use these features, you should be able to work with your existing drawing files in the latest release without making any changes. Your drawing files might need to be saved to an earlier drawing file format to exchange or use them in a previous release.
AutoCAD 2016-based products no longer support drawing file based password protection. New drawing files created in an AutoCAD 2016-based product can't be password protected. When an existing password protected drawing file is opened in an AutoCAD 2016-based product, a password is required to open the file. If the password protected drawing file is saved by the AutoCAD 2016-based product, the password is removed.
A new physical based rendering engine replaced the rendering engine used in AutoCAD 2015-based and earlier products. The change to the new rendering engine might affect the user-defined lights in your existing drawings. Standard lighting is no longer supported, any lights that were configured for standard lighting will need to be updated to use photometric lighting. Materials that are defined in your drawing might also need to be updated as a result of the way lighting is calculated. After updating the lights and materials in a drawing, you can then configure the rendering environment before rendering a drawing the first time.