The calendar is based on the oversimplified ratio of 15 Earth years to 8 Martian years, resulting in a calendar year that is short by 2.6 days.
This is a Asymmetric Zodiacal Martian calendar, wiich is defined as generally having the following characteristics:
Divide the Martian year into 12 months, symmetrically stretched to encompass the longer Martian year.
Retain the seven-day week.
Begin the year on the vernal equinox
Place the leap day(s) at the end of the year.
Base the month names on the zodiacal constellations
Calendar for Mars
| Excerpts from The Case for Mars