The second strike against HTML is its simplicity. For example, user searches cannot conveniently distinguish between Washington as president or Washington as the nation's capital, or between information about Washington the person and documents written by Washington the person. Because of the ever-increasing quantity of material on the Web, intellectual access is a major issue. And that's when the advantages of complex markup systems like those developed by the TEI become better alternatives. Consider the following example.
Letters are the most common type of documents found in documentary editions.
This is true for historical editions, literary editions, and editions which deal with the history of science, religion or any other discipline within the humanities. With this kind of markup, we begin to see how the document is organized. More striking, however, are the ways we can use the markup to infer information about the letter and other documents in the series. The more sophisticated SGML markup, in and of itself, describes only the structure of the letter. But basically, it's just a convenient way of saying one kind of data is being used to provide information about another kind data.