Effects with the expression "alternatively"

[Taurelin]

How do I have to understand the expression "alternatively" on some cards? Does it mean that I can choose between two alternatives, or does the alternative (= the other effect) automatically apply if certain conditions are met?

Example:
Not at Home
Cancel one Dragon, Drake, or Troll automatic-attack or attack keyed to a site.
Alternatively, if Gates of Morning is in play, reduce the number of strikes of any automatic-attack by 2 (to a minimum of one).

So if Gates of Morning is in play, can I still use the complete cancelling effect? I wonder especially because the German version of the card uses the wording "instead" here.


Another example:
The Cock Crows
Cancels a Troll attack. Alternatively, if Gates of Morning is in play, it forces the discard of one hazard permanent-event.

Is it possible to cancel a troll attack with GoM in play?

[zirilan]

It means that you can play the basic effect ANY time (if Doors are in play or not, if Gates in play or not) or you can chose to play the alternatively effect, if Gates / Doors are in play.

[Taurelin]

Perfect. That's what I hoped. Thx!