InstallShield 2014 ยป InstallScript Language Reference

This system variable stores the name of the current file media library or script-created feature set. During setup initialization, MEDIA is assigned the value of 'DATA', which corresponds to the file that was created by the media build. If you change the value of this system variable to refer to a script-created component set, you must change the value back to 'DATA' before calling FeatureMoveData.