SC2Mapster

@Anthius: Go

He asked how to find the things since he couldn't find it. So I pasted exactly how it wold look. Your text was an approximate of how it would look. Good enough for some, but since he asked again after, I elaborated.

Hopefully one of our detailed explanations will work for him now. :-)

Since you're checking for unit type, I assume you are using the pick all units in region option.

If can be found under Action - General - If Then Else.
Unit type == can be found under Condition - Comparison - (function) Unit Type of Unit.

When done, it should look something like this:

    Unit Group - Pick each unit in (Any units in Region 001 owned by player Any Player matching Excluded: Missile, Dead, Hidden, with at most Any Amount) and do (Actions)
        Actions
            General - If (Conditions) then do (Actions) else do (Actions)
                If
                    (Unit type of (Picked unit)) == Planetary Fortress
                Then
                    Do stuff!

Quote from dgh64: Go

Well, that would work if the P.F. is pre-placed, but it wouldn't work if the player builds their own.

Wrong.
If the P.F. is placed by a trigger or built by a player, you would store it in a variable and use that as reference.

...or if the P.F. is a generic, just any P.F. acceptable, do it like Anthius said.

Actually, the if then else isn't even needed. Just add your condition to the trigger directly. Something like this:

Fortress Alive
    Events
        Timer - Every 30.0 seconds of Game Time
    Local Variables
    Conditions
        (Planetary Fortress [20.50, 14.50] is in Fortress Area) == true
    Actions