products, the permit shall be invalidated. The Ministry of Information and Communications shall revoke this permit. 5. Within 30 days before the estimated end date of operation, the press agency must inform in writing the Ministry of Information and Communications to revoke the press operation permit and make an announcement on the mass media.  6. Where the operation permit has been revoked in accordance with the provisions in Clause 4 and 5 of this Article, if wishing the re-issue of permit, the press line agency shall request in writing the Ministry of Information and Communications to re-issue the permit. In case of change of contents compared with the issued permit, the line agency shall send dossier to request the Ministry of Information and Communications to issue the permit as stipulated in Clause 1 of this Article. Article 19. Change of the line agency of the press agency  In case of change of the line agency of the press agency, the line agency specified in the permit shall inform in writing to terminate its press activities and send it to the Ministry of Information and Communications; the agency or organization shall receive the procedures for issue of permit as stipulated in Article 18 of this Law. Article 20. Change of contents specified in the press operation permit 1. Within 05 days after the change of location of head office, telephone, fax, email, time of release, internet service provider, the press agency must inform the state management agency of the press. 2. In case of change of name of press line agency, name of press agency, principles, purposes, name of journalistic publications, supplement, special column of online newspapers, radio channels and television channels, broadcasting location, location of head office of the network operation center; mode of transmission and broadcasting; amount of time of radio channels and television channels, domain name of special column and online newspaper, the line agency must send dossier to the Ministry of Information and Communications for modification or addition of the permit. The dossier and procedures for modification or addition of the press operation permit shall be stipulated by the Minister of Information and Communications.  3. In case of change of form of presentation and location of name of publication, supplement, symbol of radio channels and television channels, publishing period, number of pages, size and the change of contents not specified in Clause 1 and 2 of this Article, the press line agency shall request in writing the Ministry of Information and Communications. The change is only made after there is a written approval from the Ministry of Information and Communications. Article 21. Type of operation and revenues of press agency. 1. The press agencies operate under the type of non-business units with revenues.