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 decoder to decode the object segment to obtain decoded graphic object data; a first buffer to store the decoded graphic object data for a predetermined time so that the decoded graphic object data remains available for use for the predetermined time; and a second buffer to store the composition information; wherein the object segment further comprises first time information according to which the the object segment is to be decoded by the decoder; and the composition segment further comprises second time information indicating an output time when the graphic screen composed based on the composition information included in the composition segment is to be output to the display device.