The screen percentage coordinate system is useful for commands where you speak the coordinates of a pointer position or offset. It has (0,0) at the upper left corner of the screen and (100,100) at the lower right corner of the screen.

CopyClick a point on the screen

<n> := 0..100;
<n> By <n> Touch = MoveToScreenPercent($2, $1) {LeftButton};

This command (invented by Kim Patch) allows clicking a point on the screen. It's much faster than using the mouse grid, and surprisingly accurate with a little practice. Saying for example "10 By 20 Touch" moves the pointer to a point near the upper left corner of the screen and presses the left button.