The Dopesheet Timeline area is an exploded view of the Action timeline in the Transport Controls window. In other words, keyframes set for different properties display separately in the Dopesheet window. When you edit visual keyframes on a Dopesheet timeline, the changes display on the Action timeline.
Dopesheet Timeline area
To zoom or magnify specific segments of the Dopesheet timeline, use the Zoom bar in the Transport Controls. The Zoom bar affects the Dopesheet timeline as well as the Action timeline.
Transport Controls window timeline A. Zoom bar
The Play Controls, Timing Controls, and the Start and End fields of the Transport Controls also affect the Dopesheet.
The Dopesheet Timeline area lets you:
