News messages use different header fields than mail messages. The Newsgroups: line is a list of comma-separated newsgroup names, which are written hierarchically somewhat like a DNS name. The Path: header line is a list of news hosts that have handled the message, separated by exclamation marks. The Distribution: header line can be used to restrict distribution of an article to a local geographic area, such as a campus or state. The Message-ID: line tags the message with a unique ID, typically including the host name of the composing host.