In a short way:
A switch trigger has to be used the same way as usual
triggers (conditions, activation fields, syncronizing, etc.)
The only difference to the usual trigger is:
The switch trigger forces events to be happening imidiately.
This means:
If you syncronize a switch trigger with let's say the 5th waypoint of a unit, the unit will move imidiately to the next
waypoint after wp nr. 5, regardless to where it actually is
(even if the unit is already at a waypoint further in the row
e.g: wp nr.
By using switch triggers, you can also break never ending
waypoints, like: cycle, guard, support, hold
Switch triggers are also very helpful, if you want to create
different seperate sets of waypoints for a unit.
e.g: wp 1 - 5 (while 5 is a type cycle wp)
wp 6 - 8 (8 = hold wp)
wp 9 - 10 (10 = guard)
wp 11 (cycle, placed close to wp 1)
If you syncronize wp 5, 8, 10 with 3 different switch triggers
(depending on which event you want to be happened), you
have 3 different kinds of waypoint sets now.
wp 1 -5 - could for example be used as a usual patrol from
1 to 5 and again and again, until 1 of the triggers becomes
activated.
WP could be used in this case as a hold and defend the base waypoint set.
WP 9-10 as a set of sending them on a hunt for the enemies
hope this helps a bit, and doesn't confuse you even more
~S~ CD