m3u files are quite simplistic in their encoding. A Standard m3u file writes a single path which can be absolute or relative to the file. Any line in the file which starts with a # character is a comment.
An Extended m3u file specifies every track's duration in seconds and its title. The file starts with a #EXTM3U comment. Every line specifying a path is preceded by a comment formatted as follows:
#EXTINF:duration in seconds,title
A Yate m3u file specifies a Yate Track ID, This enables the processing of a file to correct paths which may have moved or been renamed. While not standard the file should be read by all players as it utilizes comment lines for its encoding. The file starts with a #YATEM3U comment. Every line specifying a path is preceded by a comment formatted as follows:
#YATETID:Yate track id