Shot, a single cinematic view. In Awakening, a shot means a segment of animation; in a shot, you can animate camera, lights, etc.
Shots can be divided into two types by whether affecting camera. There are possibly many shots have affecting camera attribute, but only one shot can control the camera at one time; the PlayShot command ensure this rule, it will stop old shot before start a new shot. For those shots without affecting camera attribute, they can be activated multiply at one time; the PlayAnimate command for this purpose, it start a new shot ( the shot will not control camera no matter how its style ), and add it to active shots list. To sum up, there is one exclusive shot for camera control; and can exist multiple active shots.

shot messages:

A shot have three messages: Shot Begin, Shot End, Shot Timer. The Shot Begin and Shot End are respective triggered when start shot and stop shot. The Shot Timer message has a parameter which indicate the trigger time (unit is 0.1 sec.); for example, if you define a Shot Timer message with a 50 value parameter, then this message will be triggered after 5 seconds from shot start. 

To assign a value to the Shot Timer message's parameter, first set current time in Animation Panel, then add action for shot.

The Shot Timer messages are not stable, that's means they will not be triggered sometime as some reason. For example, if you play a shot with 32 x speed, the frame on the specified time may be skipped; another reason, if the scene rendering is slow, so can not reach 10 frames per second, also can result in skipping frame. But the Shot Timer message with 0 value parameter is a exception, it's stable and always be triggered. 

But Shot Begin and Shot Timer 0 is different in a shot has 'Circle' style, a circle shot will automatically repeat after starting.
See the illustration above, assume a circle shot with 8 second length; when playing this shot, the Shot Begin message is triggered first, and Shot Timer 0 closely followed. But Shot Begin is triggered only once, however Shot Timer 0 will be triggered on every cycle starting.