It provides a definite and extensible sensitive information model processed by access control model. This can improve the pertinence of the study of flexible access control model.
这为访问控制模型需要处理的敏感信息提供了一个明确的模型，从而提高了柔性访问控制模型研究的针对性。
Since optical ring is the main topology in metro ring, it is of great significance to study the MAC (media access control) protocol, which is discussed in this paper.
光环网是构建城域光网络的主要拓扑方式，因此研究城域光环网的MAC协议是十分必要的。
Based on the study of vulnerability information system, point out the limitation of access control mechanism.
深入分析脆弱性信息系统研究现状，指出现有脆弱性信息系统访问控制机制的不足之处。
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