Manipulating Visual Basic and Visual C# Projects
Visual Studio add-ins are deprecated in Visual Studio 2013. You should upgrade your add-ins to VSPackage extensions. For more information about upgrading, see FAQ: Converting Add-ins to VSPackage Extensions.
Although Visual Studio has a generic project automation model that enables manipulation of any project type, Visual Basic, and Visual C# have a separate, common project model that gives access to their specific properties and functionality. This model is contained in several different namespaces: VSLangProj, VSLangProj2, VSLangProj80, VSLangProj90, and VSLangProj100.
For more information about how to program in this project automation model, see Introduction to the VSProject2 Object.