Status: Patent Application (allowed in US 5/7/18, patent to issue), pending elsewhere in Europe and the world as of publication.
Description: This is such a clever idea. The basic concept is to take the relatively mundane day-night complication and make it really special, by having the moon in the day-night complication also display the phase of the moon.
The patent application discloses a couple of different gearings to make the mechanism work, but requires that the moon phase be part of the day-night, and that the aperture for the moon phase be off center, as it naturally would be.
What it means: This would allow Blancpain the exclusive right to manufacture, import, sell, or license this dual complication in any country where they are granted the patent. Blancpain would have that exclusive right until July 4, 2036, as long as they continue to pay regular fees to maintain the patent. They do not have to make watches with this complication, but they really should. It's very cool.