Double MS recording

Double MS recording is an audio recording technique used to record surround sounds using three microphones. The mid mic usually a cardioid mic like Sennheiser MKH 40 or MKH 50, the sides using a figure of 8 mic like MKH 30, and the rear using another cardioid mic like MKH 40 or MKH 50. This is usually used for recording ambiance sounds and not live music.
From these three tracks, five channels can be extracted: