Note that it's clear that (b) refers only to spaces inside quotes, because spaces outside quotes are not allowed.

> Maybe you're referring to the comment that CSV parsers should "be liberal in what you accept from others"...?

I actually don't believe in that principle. If there is a spec that everyone agrees upon, violations should be accurately and loudly diagnosed and rejected.

Both preparation of the data format and processing of that data format should be conservative. Being liberal in what is accepted has unintended negative consequences.

Be that as it may, there is no universal CSV spec, though. RFC 4180 is just someone's opinion on what CSV should be. CSV is something that has been widely implemented in numerous programs over numerous decades, in different ways.

My main point holds that if you split the string on commas and do nothing else, then one of the aspects you're neglecting to handle is the treatment of unquoted whitespace outside of a field.