The argument item in the specified position following the keyword is extracted and its value assigned to argvalue . If it contains no leading characters which can be interpreted as a floating point number, then the output argvalue is given as 0.0. If the keyword is not found for the processed command or the argument item index does not occur in the command string, then the appropriate error or warning status is output and the value of argvalue is unchanged. The value is checked against the range values, if any are specified. A range error results in the appropriate error or warning status.
Optional argument is unspecified in the keyword argument sequence.
The specified argument is not in the keyword argument sequence. The number of keyword sequence arguments is less than the specified minimum value. If there is an error completion status, then the value of argvalue is undefined.