Test result: T3|T4 "line 1 line 2?"|line 3\nline 4?
Will any more clarification help here?
…, but if you're asking "Why are there double quotes around my `T3` field?",
Partly, yes. (But not really.)
then the answer appears to be in the CSV specification[1].
Which impressions did you get from the other BaseX information sources which I pointed out?
So, the behavior you're seeing in your sample script matches the CSV RFC.
What is your opinion for the data processing of the fields “T1”, “T2” and “T4”?
Regards, Markus