CSV

Quoting Rules

• Fields containing comma, quote, or newline MUST be wrapped in double quotes
• Double quotes inside quoted fields escape as "" (two quotes), not backslash
• Unquoted fields with leading/trailing spaces—some parsers trim, some don't; quote to preserve
• Empty field ,, vs empty string ,"",—semantically different; be explicit

Delimiters

• CSV isn't always comma—detect ; (European Excel), \t (TSV), | in legacy systems
• Excel exports use system locale delimiter; semicolon common in non-US regions
• Sniff delimiter from first line but verify—header might not contain special chars

Encoding

• UTF-8 BOM (0xEF 0xBB 0xBF) breaks naive parsers but Excel needs it for UTF-8 detection
• When generating for Excel on Windows: add BOM; for programmatic use: omit BOM
• Latin-1 vs UTF-8 ambiguity—explicitly declare or detect encoding before parsing