In this sample, the piece of content named Photo Book (shown in figure 10, in the bottom layer of the tree structure) is the default content of the root folder of the library.

在这个示例中，名为Photo Book的内容块(见图10中树结构的底层)是库的根文件夹的默认内容。

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The XML Infoset is very similar to a tree structure and it is easy to construct a graph that is not a tree (just connect the nodes in such a way so that there is no obvious root node).

XML Infoset与树结构非常相似，而且易于构造不是树的图(只需以不产生明显的根节点的方式连接节点)。

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The root of the tree is referenced via the rb_root element from the cfs_rq structure (in ./kernel/sched.c).

树的根通过 rb_root 元素通过 cfs_rq 结构（在 ./kernel/sched.c 中）引用。

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