本文介绍了公用和专用分组交换数据网的现状后，说明了开展标准的增值业务系统的重要性。
In this paper, after analysing the status on public and private PSDN, the significance of standard-based value added service systems is indicated.
在城市公用事业这种自然垄断产业中实行竞争，首先要区别对待自然垄断性业务和非自然垄断性业务。
For the implementation of competition in such monopoly industry as city public utilities, difference should be firstly made between natural monopoly operations and non-natural monopoly operations.
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