Stannah 420 limit switches and schemetics

[savutano]

Hello all ,from Great White North. I understand the 3 limit switches at the front, there is also 1 limit switch at the back ,i do not understand its operation, I have no manual, and no schematics,
Any help.
Tia.
regards all

[ianb]

Front three are top limit bottom limit and the ultimate limit is in the middle. The one at the back is a slowing switch to allow a soft stop