A design issue with NLTSS that wasn't considered until years after it was removed from production was its open network architecture. In NLTSS processes were considered as virtual processors in a network with no firewalls or other restrictions. Any process could communicate freely to any other. This meant that it was not possible to do confinement even in the sense of limiting direct communication (e.g. vs. limiting covert channels such as "wall banging"). To correct this problem NLTSS would have to require capabilities to enable communication. Late development work on NLTSS such as "stream numbers" was getting close to such a facility, but by the time active development stopped in 1988 communication in NLTSS was still unconfined.