Using a SmartClip
We use the SmartClip in much the same way as we use a ScriptClip. We drop an Instance of the SmartClip onto a Timeline, in this case into a separate Layer in the clip.bird Symbol. This time however, we designate a value for our custom variable. To do so, we use the Clip Parameters Panel (select Window/Panels/Clip Parameters),

With the Instance of the SmartClip selected on the Stage, {Double-Click} the Value field and input the desired value. Be warned that this Panel can be a little problematic. The values don’t always stick, but you’ll get used to how it functions.

In this case, I’ve assigned a value of 5 to userValue. Again, an Instance of clip.bird, with the SmartClip included, needs to be placed on a Timeline and its alpha property set to 0%. When you preview the swf, the Instance will fade into view. Now however, you can use the ScriptClip/SmartClip throughout your Flash movie with the flexibility of changing the value of userValue as needed. One ScriptClip/SmartClip to control all the fade-ins throughout your movie.
You can load smartclip.fla to view the example file.