Darwin (MacOSX)-specific platform features
About the CGL API, (from [1]): CGL or Core OpenGL is the lowest accessible interface API for OpenGL. It knows nothing about windowing systems but can be used directly to find both renderer information and as a full screen or off screen interface. It is accessible from both Cocoa and Carbon and is what both NSGL and AGL are built on. A complete Pbuffer interface is also provided. Functionality is provided in via the OpenGL framework and applications can include the OpenGL.h header to access CGL's functionality. Developers can see an example of using CGL with Carbon in the Carbon CGL code sample.
Documentation and header files are found in: /System/Library/Frameworks/OpenGL.framework /System/Library/Frameworks/GLUT.framework