Musical score created with Sibelius music notation software; may be composed using software or a MIDI input device; can be used to play software instruments, but does not contain actual audio data.
SIB files can also be exported as standard MIDI (.MID) files from within Sibelius.
Program(s) that open sib files
Mac / Windows: Avid Sibelius
Information from FileInfo.com - The File Extensions Resource.
http://www.fileinfo.com/extension/sib
