Assignment within conditional. Possibly invalid Array cast operation. Non-Boolean value used where a Boolean value was expected. Invalid Date cast operation. Unknown method. Unknown property. Illogical comparison with NaN. Any comparison operation involving NaN will evaluate to false because NaN != NaN. Impossible assignment to null. Illogical comparison with null. Illogical comparison with undefined. Only untyped variables (or variables of type *) can be undefined. More than one argument has the same name. Duplicate variable definition. Negative value will become a large positive value when assigned to a uint data type. Possible missing parentheses. Missing type declaration. Missing namespace declaration (e.g. variable is not defined to be public, private, etc.). Constant not initialized. The super() statement was not called within the constructor. Missing constructor. EventHandler was not added as a listener. Unsupported ActionScript 2.0 function. Unsupported ActionScript 2.0 property. Array.toString() format has changed. Boolean() with no arguments returns false in ActionScript 3.0. Boolean() returned undefined in ActionScript 2.0. __resolve is no longer supported. Class is sealed. It cannot have members added to it dynamically. Function used in new expression returns a value. Result will be what the function returns, rather than a new instance of that function. ActionScript 3.0 iterates over an object's properties within a "for x in target" statement in random order. Use of the instanceof operator. _level is no longer supported. For more information, see the flash.display package. In ActionScript 3.0, white space is ignored and '' returns 0. Number() returns NaN in ActionScript 2.0 when the parameter is '' or contains white space. Change in scoping for the this keyword. Class methods extracted from an instance of a class will always resolve this back to that instance. In ActionScript 2.0 this is looked up dynamically based on where the method is invoked from. Inefficient use of += on a TextField. Possible usage of the ActionScript 2.0 XML class.