A low density annular grout composition for filling voids. In this game system, a disturbance area DA is set in the operation area OA when a given disturbance condition has been satisfied. The control also employs a closed loop control effort responsive to at least one preselected transmission speed error. 73 and Abbe number within a range from 50 to 60, a Tg within a range of 480-580 C. The polyester for a toner of the present invention is usable as a resin binder for a toner usable in, for example, developing electrostatic latent images formed in electrophotography, electrostatic recording method, electrostatic printing method or the like.