"never-rises" and "never-sets": the window holds no rise and no set, and
the body stayed below (polar night, for the Sun) or above (polar day) the
horizon of the conventions throughout. "outside-reference-span": the
window reaches outside REFERENCE_SPAN.
"never-rises"and"never-sets": the window holds no rise and no set, and the body stayed below (polar night, for the Sun) or above (polar day) the horizon of the conventions throughout."outside-reference-span": the window reaches outsideREFERENCE_SPAN.