The Export tag works in conjunction with the Import and Import2 tags. The Export tag gives a list of definitions made visible to the external world. Thus these definitions are in effect available to be imported by other movies.
The Export tag is a list of identifiers which are the identifiers of the objects defined within this movie and gives an external name to that object. The name is the external reference and that's what the Player will use to know how to retrieve the data from another movie. Each name need to be different, however there is no other restriction.
There should be only one Export per SWF movie. It is not clearly defined anywhere, but it is likely that the player will stop at the first export they find and not try to see if other Exports are defined in your SWF movies. It is not clear whether a movie using Export can itself Import other movies yet it is likely.
You should at least have one external reference (i.e. f_count > 0).
The identifiers defined in this list must match an object in the movie which includes this tag.