The following commands are restricted when the HIDDEN option is in play:
accept: Will only display contacted countries. country: Discloses less detailed status of active countries. newspaper: Reports on contacted countries only, except for headlines. power: Displays your own power only; other nations never show up. relations: Reports on contacted countries only. report: Reports on contacted countries only, and less status.
Commands to interact with other countries, like telegram, work only for contacted and deity countries.
A country is 'contacted' with a successful spy, look, coastwatch, recon, skywatch, by catching spies, spotting planes or sighting ships, by combat or if you receive a telegram.
It possible for contact to be one sided. If you contact someone, they must also contact you in order to obtain information from you. If you want someone to be able to contact you, you can send them a telegram.
Tech and research bleed only comes from contacted countries, so it's in your best interest to explore as much as possible.
Because of the difficulty of tracking past news, news cannot be used with an argument under this option. Once the news is read, it cannot be read again. This may change in the future.
If the LOSE_CONTACT option is in play, contact is lost after three update of no contact. Contact can be maintained by the same methods described above. It's important to note, however, that contact is retained by RECEIVING a telegram, not sending one.