While a hostname may not contain other characters, such as the underscore character ("_"), other DNS names may contain the underscore. This restriction was lifted by RFC 2181. Systems such as DomainKeys and service records use the underscore as a means to assure that their special character is not confused with hostnames. For example, "_http._sctp.www.example.com" specifies a service pointer for an SCTP-capable webserver host (www) in the domain "example.com". Notwithstanding the standard, Chrome, Firefox, Internet Explorer, Edge and Safari allow underscores in hostnames, although cookies in IE do not work correctly if any part of the hostname contains an underscore character.