Represented as an ordinal number followed by either a single .0 or a set of ordinal numbers separated by dots, the node data type corresponds to a position in a tree structure.
节点数据类型用一个序数加一个 .0 或一组以点号隔开的序数来表示,它对应于一个树结构中的一个位置。
3
This type of Topological space is GO-space or their products. The special ordinal structure of GO-space provide people extensive space to imagine and plot.