is_color_hex() validates hex color strings (#RGB, #RGBA, #RRGGBB, #RRGGBBAA).is_ipv6() validates IPv6 address strings, including compressed (::) and IPv4-embedded forms (#18).is_iso_date() and is_iso_datetime() validate ISO 8601 date and datetime strings.is_mime() validates MIME type strings against the IANA-registered top-level types.