Zgrass included three priorities (called "levels") that allowed macros to be run normally, or in "foreground" or "background" levels. This added a simple form of multitasking which was tremendously useful in an animation-oriented language. Game authors could place joystick-reading routines in a macro set to run in the background, and then the joystick would be read automatically whenever the current drawing macro completed. Functions placed in the foreground ran before either, and was often used for timers and other "low latency" needs. Zgrass included a codice_11 function that would call macros on a timed basis, making the implementation of timers very easy.