American Memory from the Library of Congress
"American Memory consists of primary source and archival materials relating to American culture and history. These historical collections are the key contribution of the Library of Congress to the National Digital Library. Most of these offerings are from the Library's unparalleled special collections.
"The Library is converting a wide array of documents to searchable form, including books, pamphlets, legal materials, serial articles, and manuscripts. The American Memory Document Type Definition (AMMEM.DTD) was developed to accommodate this broad range of materials by conceptualizing a generalized humanities text, rather than seeking to describe specific document types and subtypes, or text genres. Simple, streamlined models and flexible structure are characteristic of AMMEM.DTD.
The American Memory DTD is based on the Text Encoding Initiative (TEI), which has established a set of models and guidelines for encoding texts in the humanities."
– American Memory WWW Home Page
For a discussion of the choice of a DTD for the American Memory project, and the DTD itself, see the American Memory DTD for Historical Documents.