Prepara un valor para insertarlo de forma segura en un CSV.
Si un campo contiene el delimitador, comillas o saltos de línea, el estándar CSV exige entrecomillarlo y duplicar las comillas internas.
A field is wrapped in double quotes when it contains the delimiter, a quote or a line break. Every double quote inside becomes two double quotes.
When the field contains the delimiter, a double quote or a line break. Leading or trailing spaces are another case where quoting is safer, and the tool quotes those too.
Because the comma is the decimal separator in those locales. Set the delimiter to semicolon when the file is for a German, French or Turkish Excel.
Wrap the field in quotes and keep the line break inside. Most importers read it as part of the field.
RFC 4180 describes it, but it is a description of common practice rather than a strict rule, which is why dialects differ.