Internal Program Version:  NUT 2011.03.04  (The HEADER-Files)

Library for manipulation with NUT multimedia streams.

Unlike many popular containers, a NUT file can largely be viewed as a
byte stream, opposed to having a global block structure. NUT files
consist of a sequence of packets, which can contain global headers,
file metadata, stream headers for the individual media streams,
optional index data to accelerate seeking, and, of course, the actual
encoded media frames.

http://wiki.multimedia.cx/index.php?title=NUT