国际标准化组织ISO提出的不基于特定机型、操作系统或公司的网络体系结构OSI模型中，第2层和第4层分别为(7)。

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Although the bulk of industry resources and energies have focused on developing the fastest(71)or slickest(72)more and more mindshare is turning to the evolution of the computer interface. Advancements in the areas of input devices,(73)processing and vitual reality could lead to fundamental changes in the way human and computer interact. The technological battlefield of the future will be adding layers between the user and the raw machine to make the(74)as invisible as possible.(75)represents the next evolutionary step for the interface.

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WAP uses(66)which includes the Handheld Device Markup Language(HDML)developed by Phone.com. WML can also trace its roots to eXtensible Markup Language(XML). A markup language is a way of adding information to your(67)that tells the device receiving the content what to do with it. The best known markup language is Hypertext Markup Language.(68)HTML, WML is considered a meta. language. Basically, this means that in addition to providing predefined(69), WML lets you design your own markup language(70). WAP also allows the use of standard Internet protocols such as UDP, IP and XML.