GML is odd in a way. It creates an object and separates them into a c++ equivalent of a type of class.
The .yyz files are encrypted and can only be accessed through Game Maker Studio. If you have it, it will make viewing it much more pleasant. However, since most people don't even know what GML is, I am uploaded each object's code into a .txt file. Each "class" will be marked with a ||| C L A S S |||