The "structure view" is a hierarchical tree representation of the document being edited in the main pane.

“结构视图”是在主窗格中被编辑的文档的分层树表示。

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The Data Object Graph is the hierarchical structure of data. It contains a tree of Data Objects and another structure called the Change Summary (see Figure 4).

数据对象图是一个描述数据的分层结构，它包括一个数据对象树和另一个称作更改摘要 (Change Summary) 的结构（请参阅 图 4）。

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The practical skill required for this activity is to be able to flatten a hierarchical (tree-like) structure.

此活动所需要的实际技能是能够平面化层次(树形)结构。

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So, to cut to the logical chase, what you have is a many-to-many mapping with a hierarchical (family tree) structure.

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