| anchorsMatchLineEndings | the start and end of input anchors (^ and $) also match against the start and end of a line. | anchorsMatchLineEndings | (not portable) |
| asciiOnlyCharacterClasses | only ASCII characters when matching character classes. | asciiOnlyCharacterClasses | (not portable) |
| asciiOnlyDigits | only ASCII characters as digits | asciiOnlyDigits | (not portable) |
| asciiOnlyWhitespace | only ASCII characters as space characters | asciiOnlyWhitespace | (not portable) |
| asciiOnlyWordCharacters | only ASCII characters as word characters | asciiOnlyWordCharacters | (not portable) |
| dotMatchesNewlines | the “any” metacharacter (.) also matches against the start and end of a line. | dotMatchesNewlines | (not portable) |
| ignoresCase | ignores case when matching | ignoresCase | (not portable) |
| unicodeMatchingSemantics | use Unicode scalar matching sematics | unicodeMatchingSemantics | (not portable) |