In the SQL statement below I am passing ROUTER_ID and expecting to have the most recent version of RTR_HEADER record along with related RTR_SEQUENCE returned.
SELECT
RH.ROUTER_ID,
RH.DESCRIPTION,
RSEQ.SEQUENCE_NUMBER
FROM
CFG.RTR_SEQUENCE RSEQ
INNER JOIN CFG.RTR_HEADER RH
ON RSEQ.ROUTER_ID = RH.ROUTER_ID
AND RSEQ.ROUTER_REV = RH.ROUTER_REV
WHERE
RH.ROUTER_REV = (SELECT MAX(RVER.ROUTER_REV) FROM CFG.RTR_HEADER RVER WHERE RVER.ROUTER_ID = RH.ROUTER_ID)
AND RH.ROUTER_ID = 'XXXXX-XXX'
ORDER BY RH.ROUTER_ID, RSEQ.SEQUENCE_NUMBER
SELECT
RH.ROUTER_ID,
RH.DESCRIPTION,
RSEQ.SEQUENCE_NUMBER
FROM
CFG.RTR_SEQUENCE RSEQ,CFG.RTR_HEADER RH
WHERE RSEQ.ROUTER_ID = RH.ROUTER_ID
AND RSEQ.ROUTER_REV = RH.ROUTER_REV
AND RH.ROUTER_REV = (SELECT MAX(RVER.ROUTER_REV) FROM CFG.RTR_HEADER RVER WHERE RVER.ROUTER_ID = RH.ROUTER_ID)
AND RH.ROUTER_ID = 'XXXXX-XXX'
ORDER BY RH.ROUTER_ID, RSEQ.SEQUENCE_NUMBER