但网络的最边缘——叶子，却具有不同的结构，与木质部和韧皮部不同，叶子的纹路交叉并成环。
But the very end of such a network, the leaf, has a different architecture. Unlike the xylem and phloem, the veins in a leaf cross-link and loop.
当对象后来从其字节串重建时，内存中新建的对象与原对象具有相同的结构和值，但位于不同的内存地址。
When the object is later re-created from its byte string, it will be a new in-memory object identical in structure and value to the original, though located at a different memory address.
但空间数据具有数据量巨大，结构复杂，属性数据与空间数据密切相关，并随其反映的地理特性不同而具有不同的数据类型等特点。
Spatial data have the characteristics of huge quantity, the high correlation between attribute data and spatial data, and the different data types with the different reflective geographical entities.
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