The Chosen Days Calendar

The Chosen Days calendar is the calendar created by the Samael empire. It is divided into fourteen 28-day months. The year is divided into three phases: Sun, which is four months, Dusk, which is four months, and Moon, which is six months. Some more traditional people separate the final two months of the year into the phase of Stars, and while this is used on royal documents, it's not used much in every day life.
The Chosen Days calendar is used as a global standard. The Samael Empire has been a global superpower for over 6,000 years, and the calendar itself was already based off of an elven calendar that was already in wide use. The calendar it is based off of is a lunisolar calendar, but the CD Calendar is rigid and more strictly follows the sun.