A particular value for a variable that is assigned automatically by an operating system and remains in effect unless canceled or overridden by the operator. 預設，默認某一變數的特定值，由操作系統自動指定並持續有效，除非操作者取消它或使它無效
Establishing a value for a variable or symbol or establishing what the variable represents. 為變數或符號確定一個值，或者確定此變數代表的內容。
A variable that is given a constant value for a specified application and that may denote the application. 一種為專用應用程序而給定一個常數值的變數，而且它可以表示該應用程序。
