XSD Compound elements

Compound elements contain other elements and/or attributes.

A compound element refers to an XML element that contains other elements and/or attributes.

There are four types of compound elements:

• Empty elements

• Elements that contain other elements

• Elements containing only text

• Elements containing both elements and text

Note: All of the above elements can contain attributes!

Example of compound element

The compound element, "product", is empty:

The compound element, "employee", contains only other elements:

Compound XML element, "food", contains only the text:

Compound XML element, "description" contains elements and text:

How to define compound element?

Look at this compound XML element, "employee", containing only other elements:

In XML Schema, we have two ways to define compound elements:

1. By To name this element, you can directly declare the "employee" element, like this:

If you use the method described above, only "employee" can use the specified composite type. Notice that its child elements, "firstname" and "lastname", are enclosed in the indicator <sequence>. This means that child elements must appear in the order in which they are declared. You'll learn more about indicators in the XSD Indicators section.

2. The "employee" element can use the type attribute. The function of this attribute is to reference the name of the composite type to be used:

If you use the method described above, several elements can use the same composite type, such as this:

You can also base a compound element on top of an existing compound element and then add some elements, like this: