Defining a Custom Sort Order in SQL

I am having a hard time getting a custom sort working. The user wants
"Filters" listed first then everything else after that (they don't care
about order, but I figured listed as alpha). This is break logic on part
type. So here is the SQL statement I am trying

SELECT RVEHNO, RVEHKY, RPARTC, CBDESC, RPARTN, AMFGCD, ADESC, ABIN
FROM QMFILES.GA560AP, QMFILES.GA600AP, QMFILES.GA122AP
WHERE RPKEY = AKEY AND
RPARTC = CBCODE AND
RVEHKY IN
(SELECT DISTINCT MAX(RVEHKY) AS RVEHKY
FROM QMFILES.GA560AP
GROUP BY RVEHNO) AND
RVEHNO = 2 AND RPARTC = 2
UNION
SELECT RVEHNO, RVEHKY, RPARTC, CBDESC, RPARTN, AMFGCD, ADESC, ABIN FROM (
SELECT RVEHNO, RVEHKY, RPARTC, CBDESC, RPARTN, AMFGCD, ADESC, ABIN
FROM QMFILES.GA560AP, QMFILES.GA600AP, QMFILES.GA122AP
WHERE RPKEY = AKEY AND
RPARTC = CBCODE AND
RVEHKY IN
(SELECT DISTINCT MAX(RVEHKY) AS RVEHKY
FROM QMFILES.GA560AP
GROUP BY RVEHNO) AND
RVEHNO = 2 AND
RPARTC <> 2
ORDER BY CBDESC, RPARTC, RPARTN) AS TABLE

I was hoping that the union work work which it does, but the other items are
unsorted. Ideas?