However, there appear to be no formal XML DTDs for bibliographic data in the public domain. The following section describes how I developed bookreview.dtd to define the rules for the book review data. These declarations define the structure, descriptive and storage information for a document type. Please refer to Figure 1, the Element Content Model for Book Review Data . I declared element attributes.
Entities are variables used to define shortcuts to common text.
I used a parser, which is a program that checks for errors in your XML document, to test the validity of booksample1.xml. I also opened sample1.xml in Microsoft Internet Explorer 5.0, which is currently the only non-beta browser that supports XML documents. There were no errors, so apparently the Microsoft parser also recognizes that samplebook1.xml is a valid and well formed XML document. Basically, what this means is that booksample1.xml does not break any of the structural rules described in bookreview.dtd. These considerations are important in choosing an appropriate document type.