User Guide

Compatibility with previous versions 21
The only exception to this rule is that an ActionScript 2.0 SWF file can replace itself with
an ActionScript 3.0 SWF file, as long as the ActionScript 2.0 SWF file hasn't previously
loaded anything into any of its levels. An ActionScript 2.0 SWF file can do this through a
call to
loadMovieNum(), passing a value of 0 to the level parameter.
■ In general, SWF files written in ActionScript 1.0 or 2.0 must be migrated if they are to
work together with SWF files written in ActionScript 3.0. For example, say you created a
media player using ActionScript 2.0. The media player loads various content that was also
created using ActionScript 2.0. You cannot create new content in ActionScript 3.0 and
load it in the media player. You must migrate the video player to ActionScript 3.0.
If, however, you create a media player in ActionScript 3.0, that media player can perform
simple loads of your ActionScript 2.0 content.
The following diagram summarizes the limitations of previous versions of Flash Player in
relation to loading new content and executing code, as well as the limitations for cross-
scripting between SWF files written in different versions of ActionScript.
Supported
functionality
Run-time environment
Flash Player 7 Flash Player 8 Flash Player 9
Can load SWFs
published for
7 and earlier 8 and earlier 9 and earlier
Contains this AVM
AVM1 AVM1 AVM1 and AVM2
Runs SWFs written in
ActionScript
1.0 and 2.0 1.0 and 2.0 1.0 and 2.0, and 3.0
Supported
functionality*
* Content running in Flash Player 9 or later. Content running in Flash Player 8 or earlier can
load, display, execute, and cross-script only ActionScript 1.0 and 2.0.
Content created in
ActionScript 1.0 and 2.0 ActionScript 3.0
Can load content and
execute code in content
created in
ActionScript 1.0 and 2.0 only ActionScript 1.0 and 2.0,
and ActionScript 3.0
Can cross script content
created in
ActionScript 1.0 and 2.0 only†
† ActionScript 3.0 through Local Connection.
ActionScript 3.0‡
‡ ActionScript 1.0 and 2.0 through LocalConnection.