Minecraft wiki entry for tickingarea, associated text: Specifies the coordinates of the center point of a circular area used to define a ticking area.
It must be a three-dimensional coordinates composed of <x>, <y> and <z>, each of which must be a floating-point number or tilde and caret notation.
For x and z, numbers less than -30,000,000 or greater than 30,000,000 are treated as -30,000,000 or 30,000,000 respectively.