An item that represents a value that cannot be changed. Data type . Definition of the data. A construct which associates attributes to a variable name or function. No storage is reserved.
Variable definition is a declaration with storage allocation.
Escape sequence . Control codes comprising combinations of a backslash followed by letters or digits which represent non printing characters. Program which will run in the environment of the operating system or within an appropriate run time environment. Program which will run within the environment of the operating system without additional utilities or support. A sequence of operators and operands which may yield a single value.