Open Watcom FORTRAN 77 Language Reference

FORTRAN Statements
It should be noted that the ASSIGN statement does not assign the numeric value of the statement label to
the variable.
Example:
ASSIGN 100 TO LABEL2
PRINT *, LABEL2
Try the above example; the value printed will not be 100.
Consider the following example.
Example:
* Illegal use of a GOTO statement.
LABEL2 = 123
LABEL3 = LABEL2 + 10
GO TO LABEL3
LABEL3 is assigned the integer value 133. The assigned GO TO statement, which follows it, is illegal and
a run-time error will occur when it is executed.
Statement label values are quite different from integer values and the two should never be mixed. In the
following example, the assignment statement is illegal since it involves an integer variable that was
specified in an ASSIGN statement.
Example:
* Illegal use of an ASSIGNed variable in an expression.
ASSIGN 100 TO LABEL2
LABEL3 = LABEL2 + 10
Note that if the assignment statement was preceded by
LABEL2 = 100
the assignment statement would have been legal.
Statement Label Assignment (ASSIGN) Statement 17