Is there a documentation where Builtin functions filters null results? Below query returns 2336 rows and I can see null results for previousdoc. If I use

BUILTIN.DF(PTL1.previousDoc)

result count is decreased to 1023 with only lines where there is value.

SELECT DISTINCT
  T.tranid,
  PTL1.previousDoc
FROM TransactionLine TL 
LEFT JOIN Transaction T ON T.id = TL.transaction
LEFT JOIN PreviousTransactionLink PTL1 ON TL.transaction = PTL1.nextDoc
WHERE TL.quantity > 0 AND TL.item <> '32607' AND TL.taxLine ='F' AND TL.mainLine = 'F' AND BUILTIN.DF(T.type) = 'Purchase Order' AND TL.subsidiary = '74'

There was a conversation here earlier about BUILTIN.DF acting like an inner join ... sometimes. https://archive.netsuiteprofessionals.com/t/539018/just-a-warning-for-those-who-are-using-builtin-df-in-some-bu

Thanks for the info. It seems safer not to use.