1. An optical disc storing a data structure for managing reproduction of text subtitle stream by a reproducing apparatus, comprising: a data area storing a playlist including at least one playitem and at least first and second subplayitems, the playitem specifying a time based playing interval from in time until out time associated with at least one audio/video (AV) stream file including at least one audio/video (AV) stream and the first subplayitem specifying a time based playing interval from in time until out time associated with at least one text subtitle stream file including at least one text subtitle stream, the data area further storing the text subtitle stream including a first segment and a second segment, the first segment including region style information including a default style to be applied to a text subtitle region of a display screen by default, the second segment including text data to be displayed within the text subtitle region of the display screen and inline style information to be applied to a specific portion of the text data which overrides the region style information, wherein the first subplayitem indicates a plurality of independent text subtitle stream files having different language codes, respectively, and wherein the first subplayitem is associated with reproduction of the text subtitle stream and is synchronized with the playitem, and the second subplayitem is associated with reproduction of a browsable slideshow and is not synchronized with the playitem.
3. The optical disc of claim 1 , wherein the default style of the text subtitle region is specified by at least one of a region position, a region size, a region background color, a text position, a text flow, a text alignment, a line space, a font identification, a font style, a font size, and a font color defined in the region style information.