Once again, we reiterate that nonuniformity is an aesthetic property and thus our results are essentially only valid if one adopts our measure. Nevertheless, visual inspection of the result of its application does not refute its reasonableness. The ultimate test lies in psychological experiments.The presence of a hyphenation capability will probabily result in less of a need for the measure although it remains useful in applications such as newspapers and magazines where columns are relatively narrow. However, such a hyphenation capability does make our heuristic algorithms more attractive than the dynamic programming approach since their execution time is independent of the maximum number of word segments in a line (i.e., K). In particular, Algorithm 3 with its check for optimality for each line should yield the best results in terms of execution speed. The garbage compaction algorithm described works in linear time and, for the most part, does not require any work space. It combines marking and compaction into a two-step algorithm that is considerably faster than, for example, Morris's method. The first step marks all nongarbage cells and, at the same time, rearranges the pointers such that the cells can be moved; the second step performs the actual compaction.

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This paper describes the configuration and intermodule communication of a MULTImodule system for supporting Secure Authorization with Full Enforcement (MULTISAFE) for database management. A modular architecture is described which provides secure, controlled access to shared data in a multiuser environment, with low performance penalties, even for complex protection policies. The primary mechanisms are structured and verifiable. The entire approach is immediately extendible to distributed protection of distributed data. The system includes a user and applications module (IJAM), a data storage and retrieval module (SRM), and a protection and security module (PSM). The control of intermodule communication is based on a data abstraction approach, initially described in terms of function invocations. An implementation within a formal message system is then described. The discussion of function invocations begins with the single terminal case and extends to the multiterminal case. Some physical implementation aspects are also discussed, and some examples of message sequences are given.

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