The security of the system can be improved by multilevel filter.
这样通过多级过滤提高系统的安全性。
The integrated model can simplify administration of privileges, and is appropriate for multilevel relation database system which has many users or complex security levels.
该模型方便了管理员的权限管理，适合用户较多，安全层次比较复杂的多级关系数据库系统。
A multilevel real-time database system must have security constrains in addition to timing constrains.
一个多级安全实时数据库系统不仅需要有安全限制，同时也要有时间约束。
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