There are twelve zodiac signs according to the Indian system of Astrology.
The four phases that come under each zodiac sign is based on Vaastu concept.
According to this, the first 7 1/2 degrees in each sign have been
attributed to the first phase, 15 degress to the second phase, 22 1/2 degrees to the third phase and 30 degress to the last phase.
Totally there are 40 different formulas of Vaastu for the zodiac signs.