De-click Mid Side mode

[cheakypawl]

What is the significance of this option? When should it be used or not? Manual states, but explains nothing further, unless I've missed it... thank you.

"M/S mode
The Mid / Side (M/S) mode is only available when working with source material in stereo. When enabled, the incoming audio is converted to a M/S signal prior to processing and decoded back to normal left / right stereo at the output."