2.3 An XML Primer

Flashing text did not become a standard HTML markup tag. Neither is it an official XML tag either. In fact there are no official XML tags XML is a syntax for creating markup languages, not a markup language itself. XML is a text-based standard, and can usually be read by a human. A short example is shown in Fig 2.1, easily understandable without even the slightest knowledge of the situation.

 Fred Smith 
 93 Example Avenue Ipswich Suffolk IP50 9BT 
 

The angle brackets (< and >) denote tags. There are two types of tag a start tag and an end tag. Inside a start tag there is a (usually self-describing) word, called the element and optionally a number of attributes. An attribute is a pair of words consisting of a name and a value and written in the form: x = " y", where x is the name and y is the value. Therefore, in the example, the elements are 'customer', 'name', 'address', 'street', 'city', 'region', 'postcode' and 'status' while the attributes are 'country', 'purchases' and 'last-purchase'. An end tag contains a forward-slash and an element name that matches the element of the start tag. Each opening tag has a complementing closing tag with the same word between the angle brackets except for the forward-slash at the beginning. Between start and end tags there can be text known as character data