自标准实施之日起，至标准重申重新确认、修改或废止的时间，称为标准的有效期(标龄)，我国的国家标准有效期一般为(48)年，国家标准是由政府或国家级的机构制定或批准的，适用于全国范围的标准，是一个国家标准体系的主体和基础，国内各级标准必须服从且不得与之相抵触。(49)是中华人民共和国国家标准，我国国家批准的软件工程国家标准有基础标准、开发标准、(50)、管理标准。CMM分为5个成熟等级，其中企业一般缺少有效的管理，不具备稳定的软件开发与维护环境称为(51)，而企业建立了基本的项目管理过程的政策和管理规程，对成本、进度和功能进行监控，以加强过程能力称为(52)。

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While the Internet is inherently insecure, businesses still need to preserve the privacy of data as it travels over the network. To help do that, the Internet Engineering Task Force an international group of network designers, operators, vendors, and researchers concerned with the evolution of(71)has developed a suite of(72)called Internet Protocol Security(IPSec).

 IPSec creates a standard platform. to develop secure networks and electronic(73)between two machines. Secure tunneling via IPSec creates(74)connections in a network through which data packets can move. It creates these tunnels between remote users and within a local network. It also(75)each data packet in a new packet that contains the information neccessary to set up, maintain and tear down the tunnel when it's no longer needed.

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One of the difficulties in building an SQL-like query lange for the Web is the absence of a database schema for this huge, heterogeneous repository of information. However, if we are interested in HTML documents only, we can construct a virtual(66)from the implicit structure of these files. Thus, at the highest level of(67), every such document is identified by its Uniform. Resource Locator(URL), has a title and a text Also, Web servers provide some additional information such as the type, length, and the last modification date of a document. So, for data mining purposes, we can consider the site of all HTML documents as arelation:

 Document(url,(68), text, type, length, modify)

 Where all the(69)are character strings. In this framework, anindividual document is identified with a(70)in this relation. Of course, if some optional information is missing from the HTML document, the associate fields will de left blank, but this is not uncommon in any database.

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