You can find the complete specification for the GL_ARB_multisample extension in the OpenGL extensions registry at http://oss.sgi.com/projects/ogl-sample/registry/.
If your application needs point or line anti-aliasing instead of full scene anti-aliasing, use the built in OpenGL point and line anti-aliasing functions. These are described in Section 3.4.2 in the OpenGL Specification.
Last updated: 2008-06-09