可扩展标记语言，标准通用标记语言的子集，一种用于标记电子文件使其具有结构性的标记语言。它可以用来标记数据、定义数据类型，-Extensible markup language, a subset of the standard generalized markup language, a kind of the structural markup language used to mark the electronic file. It can be used to tag data, the data type is defined,