OUT parameter functionality

Question

I thought that you are not supposed to be able to assign the value of an out parameter to a variable (Feuerstein, 5th ed) and yet I was just
able to do this without any compilation error messages. Is Feuerstein wrong or am I missing something? Has the functionality changed?
PROCEDURE Parse_HC
          (p_timestamp_string IN VARCHAR2,
          p_timestamp_date OUT DATE)
AS
v_date DATE;
BEGIN
p_timestamp_date := TO_DATE(p_timestamp_string, 'YYMMDDHH24MI');
v_date := p_timestamp_date;
END Parse_HC;
Here is my banner:
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Oracle Database 11g Enterprise Edition Release 11.1.0.7.0 - 64bit Production
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Answer 1

>
He said, on p583 of "Oracle PL/SQL Programming":
"You cannot assign an OUT parameter's value to another variable or even use it in a reassignment to itself."
I think his reasoning is that OUT parameters are write-only; thus, since they can't be read, one can't assign them to a variable.
But, based on the result of my code, that's not true. But perhaps I misunderstand his point.
>
Well this shows that (vanilla 11.2.0.1.0) you can assign the OUT multiple times and assign it to your var multiple times.
CREATE OR REPLACE PROCEDURE Parse_HC
(p_timestamp_string IN VARCHAR2,
p_timestamp_date OUT DATE)
AS
v_date DATE;
BEGIN
dbms_output.put_line('v_date initial:' || v_date);
p_timestamp_date := TO_DATE(p_timestamp_string, 'YYMMDDHH24MI');
v_date := p_timestamp_date;
dbms_output.put_line('v_date after:' || v_date);
p_timestamp_date := sysdate + 2;
v_date := p_timestamp_date;
dbms_output.put_line('v_date after 2nd:' || v_date);
END Parse_HC;
declare
mydate date;
begin
parse_hc('1303251425', mydate);
dbms_output.put_line(mydate);
end;
v_date initial:
v_date after:25-MAR-13
v_date after 2nd:27-MAR-13
27-MAR-13