This document describes the carriage of some forms of timed text and subtitle streams in files based on ISO/IEC 14496-12 (the ISO base media file format). The documentation of these forms does not preclude other definition of carriage of timed text or subtitles; see, for example, 3GPP Timed Text (3GPP TS 26.245), or the carriage of captioning information embedded in a media stream of another type (see Annex A).