可以将前缀设置成不同的URI，但不能取消定义，至少对XML 1.0文档是这样。

Prefixes can be set to different URIs, but cannot be undefined, at least for XML 1.0 documents.

youdao

注意设置一个名称空间的上下文不会写出名称空间声明——它仅定义前缀绑定。

Note that setting a namespace context does not cause the namespace declarations to be written out — it just defines the prefix bindings.

youdao

如果想要增加其它词汇，你只需简单地设置适当的前缀映射就可以了。

If you wanted to add in other vocabularies, it would be easy to do so as long as you set up the appropriate prefix mappings.

youdao