5.1 surround sound is the common name for six channel surround sound audio systems. It uses five full bandwidth channels and one low-frequency effects channel (the “point one”).
Yes I am aware that the the current standard is 6 track 5.1 and 8 track 7.1. What i was referring to was back in the late 60s through the early 80s. Films 35-70mm would have a magnetic soundtrack strip on them which would carry 6 channel discrete surround. I thought that the track labeled 70mm 6 Track was a recording of one of these mag tracks. Thanks for telling me it is true 5.1 though, less work for me 🙂