AS3 source architecture

I am trying to view the base class source files but not all of them are where I expect them to be.

Most of them can be found here:
Program Files\Adobe\Adobe Flash CS3\en\First Run\Classes

I would expect flash.display.sprite to be located under …\FP9\flash\display, but only the BitMap class is there.
I would expect the flash.display.MovieClip to be there as well but it is under the …\FP9 directory.