M3U
From Just Solve the File Format Problem
M3U is a plain text file listing of files for a play list. Originally ASCII later revisions use Unicode 8.
M3U files are directory location listings of specific files on an individual user’s computer. Late MPX, occasionally mistyped as m3u files, point to internet address.
For advanced users, an mpu/m3u file can point to any file on any platform via any transmission method: the most common minority variable being FTP.