Whether a rule's selectors matched anything to compare in this model. A rule with an empty a side, or (for a two-sided rule) an empty b side, never ran a single geometric comparison — it isn't "clean", it never ran.
a
b
Whether a rule's selectors matched anything to compare in this model. A rule with an empty
aside, or (for a two-sided rule) an emptybside, never ran a single geometric comparison — it isn't "clean", it never ran.