There’s no formal spec for CSV. The RFC you mentioned describes the most common behaviour observed in many implementations, but it’s not a spec itself, as mentioned on the second page:
While there are various specifications and implementations for the
CSV format (for ex. [4], [5], [6] and [7]), there is no formal
specification in existence, which allows for a wide variety of
interpretations of CSV files. This section documents the format that
seems to be followed by most implementations:
There’s no formal spec for CSV. The RFC you mentioned describes the most common behaviour observed in many implementations, but it’s not a spec itself, as mentioned on the second page: