The case study website maintains the descriptions of the case studies as XML (extensible markup language) files. XML has a similar syntax to HTML, the language of web pages, but allows the explicit representation of information and relationships, without specifying how such information should be presented. XML allows data to be manipulated by automated scripts and converted to multiple display schemes.
In the case study website, XML is converted to two different presentations: interactive on-screen, and printable. The separation of data representation from display details allows authors to focus on content without worrying about layout. It also enables a consistent look-and-feel across the web site.
A collection of files coded in XML can be thought of as a database, a set of data and relationships. Like a relational database, an XML database requires a schema, which is the vocabulary of data types and relationships that can be represented. In order to communicate, people must agree on the meanings of the words they use. In the same way, a schema enables reliable communication between authors and readers, both human and automated.
The terms in an XML schema are referenced in documents using tags, such as <Title>. A region of a document is associated with a term by surrounding it with corresponding tags, such as
<Title>My Case Study</Title>
Note that the two tags refer to the same term but differ in that the end tag has a slash before the tag name. A pair of corresponding start and end tags and the intervening content are called an element. Elements are the basic building blocks of an XML database. Relationships between elements are represented by placing one element inside another (nesting) or by linking. Nesting is the primary means used by the case study schema.
The case study schema defines the following XML element types:
In addition, the schema recognizes a subset of the standard HTML and MathML languages for representing formatted text and math, respectively. A large number of character entities are made available for including symbols and special characters in the text.