Flash CS3 Documentation

Learning ActionScript 2.0 in Adobe Flash > Data and Data Types > About variables > About default values

About default values

A default value is the value that a variable contains before you set its value. You initialize a variable when you set its value for the first time. If you declare a variable, but do not set its value, that variable is uninitialized. The value of an uninitialized variable defaults to the value undefined. For more information on creating and using variables, see About variables.

Flash CS3