Force TO_CHAR to eliminate the leading blank during display

I wrote a small SQLPLUS script to convert the Oracle data to an ASCII file. As you can see from the script, I had 1 numeric field in the table. In addition, I also put out 4 '|'s as field delimiters. QUESTION: How come there is alwayw an extra blank preceeding the numeric field (Argument_Number), even though I explicitly set "space 0", and provided the TO_CHAR function with a format of '09'.

• SQLPLUS Script *

  ---

spool trargs.txt
TTITLE off
set heading off
set linesize 78
set pagesize 0
set feedback off
set space 0

select

    Function, '|',
    TO_CHAR(Argument_Number,'09'), '|',     Description, '|',
    Data_Type, '|'
    from TRANSFORMATION_ARGUMENTS order by 1 ASC, 3 ASC; spool off
exit

CREATE TABLE TRANSFORMATION_ARGUMENTS
(

    Function CHAR(30) NOT NULL,
    Argument_Number NUMBER(2) NOT NULL,

    Description     CHAR(40),
    Data_Type       CHAR(1)

Are_Lists_The_Same            | 01|First generic list                      |G|
Are_Lists_The_Same            | 02|Second generic list                     |G|
Extract_Sub_List              | 01|Original generic list                   |G|
Extract_Sub_List              | 02|Index of comparison column              |I|