Policy files are XML files that enable you to enforce the restrictions or policies of your company or development team and are written in the Enterprise Template Definition Language (TDL). The policy files contain information and restrictions on every project that can be included in a solution.
Just like any programming language API, TDL has many options with specific parameters. In the old days, this was the reason for carrying a large book that contained the definitions and available parameters for the API. However, with the introduction of Intellisense and code completion, those books have become unnecessary. If you edit a TDL file with Visual Studio .NET, you will immediately see that you made the correct decision as Visual ...