This example map shows how to create a sequence of sequences...
You walk into this room where a citizen stands.
You want to go past him but he is blocking the way! (what an ass)
So, you go back, but when you turn around the citizen walks away from the door, and goes to the window instead and a new looped sequence begins.
Scripts might seem easy but they can be a real pain in the ass (ask habboi).
That's what makes these scripts a bit more advanced than just one script.
A bit more detailed description about what this example shows:
It shows how to loop an animation forever, but also how to end the looped script using an "exit animation".
For example, if you have a looped animation of a sitting citizen, then an exit animation would be the animation of the citizen rising from the chair he is sitting on.
The example also shows how to block the player from ruening the scripts using disabled ai.
Another small thing the example shows is how to first disable a trigger, and then enable it using another trigger.
Enjoy.
It was used in a very short scene in HL2.