In which tablespace are procedures and functions stored

I was under the impression that the procedures, functions and packages which belong to a user are stored in the default tablespace allocated to that user. However it doesn't seem so. It seems the code is stored in SYSTEM tablespace. Here's a test I did to prove that the code is not stored in the user's default tablespace:

The obvious choice to do this is SCOTT schema.  But SCOTT schema is not a part of ERP.  Here's what you do:

cd $ORACLE_HOME/rdbms/admin

sqlplus /nolog

conn / as sysdba

@utlsampl.sql

This will create the scott schema.  But scott's default tablespace is SYSTEM.  We'll change that.

CREATE TABLESPACE SCOTTD DATAFILE '/stage11i/dbdata/data1/scottd1.dbf' SIZE 10M;

ALTER USER SCOTT DEFAULT TABLESPACE SCOTTD;

CREATE OR REPLACE PACKAGE PACK1 AS

PROCEDURE PROC1;

FUNCTION FUN1 RETURN VARCHAR2;

END PACK1;

/

CREATE OR REPLACE PACKAGE BODY PACK1 AS

        PROCEDURE PROC1 IS

                BEGIN

                DBMS_OUTPUT.PUT_LINE('Hi a message from procedure PROC1');

                END PROC1;

        FUNCTION FUN1 RETURN VARCHAR2 IS

                BEGIN

                RETURN ('Hello from function FUN1');

        END FUN1;

END PACK1;

/

set serveroutput on

SQL> EXEC PACK1.PROC1

Hi a message from procedure PROC1

PL/SQL procedure successfully completed.

SQL> select pack1.fun1 from dual;

FUN1

--------------------------------------------------------------------------------

Hello from function FUN1

SQL>

CONN / AS SYSDBA

DROP TABLESPACE SCOTTD INCLUDING CONTENTS AND DATAFILES;

conn scott/tiger

SQL> EXEC PACK1.PROC1

Hi a message from procedure PROC1

PL/SQL procedure successfully completed.

SQL> select pack1.fun1 from dual;

FUN1

--------------------------------------------------------------------------------

Hello from function FUN1

SQL>

Even after dropping the default tablespace of scott, the package pack1 exists.  So source code like is not stored in default tablespace of a schema.  It is stored in SYSTEM tablespace.