Behind the Green Door secure communications center with SIPRNET, GWAN, NSANET, and JWICS access
According to the U.S. Department of State Web Development Handbook, domain structure and naming conventions are the same as for the open internet, except for the addition of a second-level domain, like, e.g., "sgov" between state and gov: openforum.state.sgov.gov.[3] Files originating from SIPRNet are marked by a header tag "SIPDIS" (SIPrnet DIStribution).[4] A corresponding second-level domain smil.mil exists for DoD users.[5]
Access is also available to a "...small pool of trusted allies, including Australia, Canada, the United Kingdom and New Zealand...".[6] This group (including the US) is known as the Five Eyes.