Hello, Xabi. Illuminates the plants on the flap or on the inside flap of the front cover of the manual. The Old Moon: from when we see the Full Moon to when the New Moon gets smaller. That is, a distance between a full moon and the new moon, about a fortnight.
It's the inverse of the new moon. It's the fortnight we see the new moon grow.
In Euskera it is known as the Old Moon and the Wandering Moon, both indicate the phase after the Full Moon. In Spanish it is called a decreasing moon and in French lune decroissante.