Problem of "create type"

Question

I have following package. If I put the definition myTableType outside the package, i.e. if I execute "create myTableType as table of char(2)", then the package has no problems. But if I put the definition inside pk_test, then it will return an error. Does anyone know why? Thanks in advance.
create or replace package body pk_test is
procedure sp_test
is
type myTableType is table of char(2);
l_data myTableType := myTabletype();
ls_item_desc char(20);
begin
dbms_output.enable(50000);
l_data.extend;
l_data(1) := '01';
select item_desc
into ls_item_desc
from item_code
where item_code in
( select * from
table(cast(l_data as sp_test.mytableType )));
dbms_output.put_line('item desc: ' || ls_item_desc);
end sp_test;
end pk_test;

Answer 1

select item_desc
into ls_item_desc
from item_code
where item_code in
( select * from
table(cast(l_data as sp_test.mytableType )));
Cannot use casting of type if not present in the db dictionary.