The banned.h header file is a sanitizing resource which supports the SDL requirement to remove banned functions from code. It lists all banned APIs and allows any developer to locate them in code. By including this header file, then using #include "banned.h" you will be able to locate any banned functions in your code. The full list of banned APIs is also included in the header file.
Sanitizing your code to remove potentially insecure APIs is a vital protection practice. Whether you include the banned.h header file, utilize the banned API Extension in the Visual Studio 2010 IDE, or leverage the /W4-C4996 warnings in the VS 2005 compiler, you now have three seamless ways to check your code and meet another SDL requirement during development.