What is an Instance ?
An instance is simply an image in an Animation Layer, an image whose duration can be adjusted.
Each instance in the timeline has now two small rectangles which allow to use this feature. The one at the bottom on the right is for stretching the duration of the current instance. To do so, simply click on this little handle (its color will then turn to light blue) and move it as shown opposite.
You have just increased the duration of the current image. Any image of an Animation Layer is considered as an instance. Of course, if you stretch an instance, the following instances will shift back :
Original layer
Extend Exposure Cells without [Ctrl] key
If you pull on the left, your instance will decrease to the head's instance (the first image).
You will notice another rectangle on your instances, on the left at the top, this time. This handle allows you to stretch an instance without modifying the total duration of your animation.
Hold the click on the handle (that will become green) and move on the left or the right :
By default, empty instances will be marked with an horizontal line to make them easy to spot. You can change this behaviour by deactivation the Differentiate Empty Instances and Put an X Mark… options from the Preferences > Display panel, as seen in lesson 1.
Look of an empty instance with one of the aforementioned options turned on