Olá Charles,
A resposta curta é nenhuma
Tente algo assim:
select
T0.DocNum as [Número do OC],
T1.LineNum as [Linha do OC],
T3.DocNum as [Número do OV],
T2.LineNum as [Linha do OV]
from
OPOR T0
inner join POR1 T1 on T1.DocEntry = T0.DocEntry
left outer join RDR1 T2 on T2.DocEntry = T1.BaseEntry and T2.LineNum = T1.BaseLine and T1.BaseType = 17
left outer join ORDR T3 on T2.DocEntry = T3.DocEntry
where
T0.DocNum = 5
Cumprimentos,
Owen