How to use the type of CREATE TYPE?

Hi,

[Quoted] I am new to the CREATE TYPE, CREATE TYPE BODY. I would like to create a type of an array of string and it would be used in PL/SQL package. However, I found that I could not use it. My case is as followed :

CREATE TYPE arr_string AS TABLE OF VARCHAR2;

CREATE OR REPLACE PACKAGE tools AS

   FUNCTION splitString(

            PIV_string IN VARCHAR2,
            PIN_break  IN NUMBER,
            PIO_string OUT arr_string
           )

When I compile this package specification, error will appear. It said that object arr_string is invalid.

What should I do ? Besides, can anyone tell me other examples about create type(except the ones on the SQL reference of Oracle menu)?

Thanks a lot.

--
Patrick Lo