The country codes have been derived from the International Organization for Standardization standard ISO 3166. At the bottom of the table, there is also a section of general top level domains, based on the information available at rs.internic.net. This includes 'telnet', 'ftp', and internet E-mail. If this is not preceded by FI or B, it means that the connection may be a UUCP connection. An asterisk is included after FI or B for consistency.
P stands for provisional connection.
It is assumed that the FIDO connection in this case is stable and reliable. It is generally possible to assume that wherever there is a U.S. military base, there will be a node reachable through gateways. However the connection may take place via UUCP and cost a lot of money. Those networks have therefore not been included. X.400 E-mail is usually charged to someone and if the telecommunication carrier cannot find someone to pay for the message transfer, it will reject it.