Compatibility of Action Script with earlier versions

There are some compatibility issue with the Flash Player 9. These compatibility issue includes the following:

• We can not combine Action Script 1.0 or 2.0 code with 3.0 code in a single SWF file.
• Action Script 3 can load SWF file that is programmed in 1.0 or 2.0 but can not access its variables or functions.
• SWF that is written by using Action Script 1.0 or 2.0 cant load SWF that is written using Action Script3.