A picture speaks 1000 words and excellent questions which i can clarify.
It only changes the Heating & Hot Water Timer/Run/Inhibit mode to what’s described in the manual as “Server Control” - it allows you to modify the prohibit status.
Server Control Mode must be enabled via the toggle switch for you to modify the prohibit status - it is not enabled by default
It displays this “globe” symbol on the FTC controller:
You can see though that the normal Run/Timer/Prohibit options dissapear from the screen though.