In April 1977, research began on the Data Communications Network Architecture (DCNA) to enable mutual use of resources among different types of computers. This joint research was conducted by five companies (the Electrical Communication Laboratories of Nippon Telegraph and Telephone Public Corporation, NEC, Hitachi, Fujitsu, and Oki Electric Industry). It was done against a backdrop of progress in networking, greater sophistication and diversification of terminal capabilities, and progress toward higher-level communications line networks (packet switching and digital integration). The goals were to achieve connectivity between online systems and to distribute communications capabilities to terminals. The first version, covering logical structure and message transmission, was introduced in March 1978, and Version 3 was developed in March 1980. This brought together the elements of a protocol system necessary for a data communication network. The system was expanded to achieve compliance with INS international standards starting in April 1980. In March 1983, DCNA motivated international standards such as OSI Transport, and the joint development finished with Version 5 (March 1983).