Whatever you want your object to do, the Action needs to be set off by some event. For instance, when other people left-click on your object that event can be used to trigger one or more commands. The trigger you choose determines what needs to happen in order for your object to execute the commands that follow it.

The available triggers are as follows:

CREATE starts the commands that follow it, when the object is first loaded into the scene. This trigger also starts its commands when the object is loaded back into the scene after having been out of visibility range, and whenever the object is edited and the changes to the object load into the scene.

BUMP starts the commands that follow it, when you bump into a solid object or pass through a nonsolid object. You can't trigger objects if you pass through them using the passthrough function, which is assigned to the SHIFT key by default.

ACTIVATE starts the commands that follow it, when the object is left-clicked on.

There is also one pseudo-trigger which happens when a the animate command reaches the end of it's animation in non-looping mode:

ADONE starts the commands that follow it, when the object reaches the end of a non-looping animation. This is called a pseudo-trigger because it requires the help of commands such as animate and astart, which in turn must be started by a trigger. Here is an example of how the adone pseudo-trigger works:

activate animate mask me fw 13 13 100, astart; adone noise boom1

Each trigger may be followed by either a single command or a comma separated list of commands.

To use more than one trigger on a single object, place a semicolon before each additional trigger.