Add a Blank Keyframe
Flash CS3 Tutorial
How to Add a Blank Keyframe in Flash
Blank keyframes are handy if you wish to start with an empty frame and add content or have your content disappear temporarily.
Add a rectangular object to the workspace with the Rectangle tool (r key).
The layer with the rectangle has one keyframe by default at frame one.
Click frame 10 and press F6 (Insert > Timeline > Keyframe). A new keyframe is added that contains the same content as frame one.
Click frame 11 and press F7 (Insert > Timeline > Blank Keyframe).
Click frame 20 and press F5 (Insert > Timeline > Frame).
Test your movie (Control > Test Movie) (Cmd/Return (PC-Ctrl/Enter) to view the animation.
The rectangle should appear at frame one and be visible until frame 11. It remains invisible until frame 20 where the animation returns to frame one and replays the movie.