This is one of the old issues with XML, that it is used for both data (machine-readable information) and content (human-legible text).
XML的老问题之一，即同时用于数据(机器可读的信息)和内容(人类易懂的文本)。
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We show how to express simple and more complex datasets using RDFa, and in particular how to turn the existing human-visible text and links into machine-readable data without repeating content.