Reports & Discoverer :: Multiple Columns In Param Form

I am adding a parameter to the parameter form of existing reports based on a select statement and has two columns. That part is fine. However, Oracle reports is adding a dash between the two values. Still fine, but I am also adding a UNION with ALL in case the user wants to run the report for all values. In the Parameter form it looks like this:

ALL -
RBC - 111
RRG - 234
TEB - 445

How do I get rid of the dash for "ALL" since I did not physically add it? Below is my select statement for the parameter I created:

SELECT code,
code_num
FROM codes
WHERE code_num <> 0
UNION
SELECT 'ALL', ' '
FROM dual
ORDER BY 1;