Given that willful copyright infringement can carry a fine up to $150k per instance, a mere 140 copies of the offending OS could attract a $21 million fine. Given that ~3 million iPads with the clock shipped in the first weekend it was available, the fine for those devices alone would approach half a trillion dollars. With an entire month's worth of sales out the door, the Swiss Railway could end up owning Apple several times over - if Apple suffered the maximum fine.

Of course, all of this is completely insane. And it's not like Apple's legal folks would take an existential threat lying down. Even so, it still reflects the lunatic reality of copyright law, which is something that any sane legal team will go out of its way to avoid. That being the case, $21 million represents an extraordinarily good settlement.