Global flag indicating that all calls will be made synchronously by default.
First available in version 3.5.
Available only in ActionScript 3.
Property; You can set this property at any point, and even bracket calls by setting it before a call and then resetting it after a call.
Setting this property to true will have no affect for the following cases:
a) a command is called with a callback object and the sync parameter is not set to true.
b) a command is called to a method that does not support synchronous calls (async-only).
Setting this property to false will have no effect for the following case:
a) a command is called with a callback object and the sync parameter is set to true.