So called Arabic parts are derived by adding and subtracting particular planetary, zodiacal positions and cuspal points in absolute longitude to synthesise a part of Lot that has symbolic meaning. It is also often defined as a system of named sensitive points made popular by Arab astrologers working with Babylonion, Egyption, and Greek sources. Abu Ma'shar wrote he learned ninety-seven of the parts from the first two sources. The Part of Fortune is commonly used by modern astrologers. Horary astrologers make use of others, such as the part of death, "find," and marriage.