The dynamic nature of business workflows can be analyzed in a two-layer model, as shown in the layered hierarchy in Figure 1.
业务工作流程的动态本质可以在一个两层的模型中进行分析，如图1中的分层结构所示。
However, I typically work this stuff in as I am developing the spread which can add another layer of texture to the composition and be used to strengthen the hierarchy of the spread.
但我通常在开始制作扩展图的时候就开始着手这些素材的填充，我们可以对于这个组的这个纹理增加一个新的图层，这样也有助于增强扩展图的层次性。
USB protocol layer describes the grammar and protocol used in the communication of USB host with USB devices, and presents the USB hierarchy consisting of fields, packets, transactions and transfers.
US B协议层描述了USB主机与usb设备交互时的语法和协议，从中定义了字段、包、事务和传送的结构，以及由字段到包、由包到事务、由事务到传送所组成的组织层次关系。
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