Author XML Elements

This topic provides basic information about XML elements.

What Is an XML Element?

XML is a meta-markup language, a set of rules for creating semantic tags used to describe data. An XML element is made up of a start tag, an end tag, and data in between. The start and end tags describe the data within the tags, which is considered the value of the element. For example, the following XML element is a <director> element with the value Matthew Dunn.

<director>Matthew Dunn</director>

The element name <director> allows you to mark up the value Matthew Dunn semantically, so you can differentiate that particular bit of data from another, similar bit of data. For example, there might be another element with the value Matthew Dunn:

<actor>Matthew Dunn</actor>

Because each element has a different tag name, you can easily tell that one element refers to Matthew Dunn, the director, while the other refers to Matthew Dunn, the actor*.* If there were no way to mark up the data semantically, having two elements with the same value might cause confusion.

In addition, XML tags are case-sensitive, so the following are each a different element.

<City> <CITY> <city>

Attributes

An element can optionally contain one or more attributes. An attribute is a name-value pair separated by an equal sign (=).

<CITY ZIP="01085">Westfield</CITY>

In this example, ZIP="01085" is an attribute of the <CITY> element. Attributes are used to attach additional, secondary information to an element, usually meta information. Attributes can also accept default values, while elements cannot. Each attribute of an element can be specified only once, but in any order.

Check the Syntax

Because XML is a highly structured language, it is important that all XML be well-formed. That is, the XML must have both a start tag and end tag, and must be authored using the proper syntax.