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  A variable is simply a named memory location with a fixed data type. As explained earlier, variables do not have to be declared in advance if the data type implied by the first letter of the name is appropriate. Otherwise a type statement is required.

At the start of execution the value of each variable is undefined unless a suitable DATA statement appears in the program unit (see section 11). Undefined values must not be used in expressions. Local variables in procedures do not necessarily retain their values from one invocation of the procedure to another unless a suitable SAVE statement is provided (section 9.11).

Helen Rowlands