Abstract: A door operator system for slidable doors comprises an expandable and retractable lattice assembly adapted for connection between a door and a stationary structure. The lattice assembly includes forward and rearward link arms connected together at a pivot joint to form a link arm pair. Several link arm pairs may be pivotally joined together to form the expandable and retractable lattice assembly, such that the distance between a retracted position and an expanded position of the lattice assembly is relatively long. An actuator with a relatively short stroke length has a housing and a shaft that reciprocates with respect to the housing between retracted and extended positions. The housing is connected to a pivot joint of one pair of link arms and the reciprocal shaft is connected to a juxtaposed pivot joint of another pair of link arms.