1. An apparatus for processing graphic data, the apparatus comprising: a reader to read data from an information storage medium, the data comprising a display set comprising an object segment and a composition segment, the object segment comprising graphic object data defining a graphic object to be used by the apparatus in composing a graphic screen to be displayed on a display device, and the composition segment comprising composition information for the graphic object defined by the graphic object data to be used by the apparatus in composing the graphic screen, the composition information specifying how the graphic object is to be displayed on the graphic screen; a first buffer to store the graphic object data for a predetermined time so that the graphic object data remains available for use for the predetermined time; and a second buffer to store the composition information; wherein the composition information comprises time information indicating an output time when the graphic object data stored in the first buffer is to be output to the display device.