SMPTE ST 429-5 PDF

This standard specifies the format of a Generic Container (GC) for XML timed text and Timed Text Track File for the distribution of timed text content using the Material Exchange Format (MXF). The GC and Track File provide for carriage of an XML document and optional supporting resources such as images or fonts. Encryption is optionally available for protecting against unauthorized disclosure of the file contents.

The standard defines data structures for interchange at the signal interfaces of networks or storage media, but does not define internal storage formats for compliant devices.