What are simple elements? ¶

Simple elements are those that contain only text. It does not contain any other elements or attributes.

However, the limitation of “text only” can easily be misunderstood. There are many types of text. It can be one of the types included in the XML Schema definition (Boolean, string, data, etc.), or it can be a custom type that you define yourself.

You can also limit its content by adding qualifications (that is, facets) to the data type, or you can require the data to match a particular schema.

Define simple elements ¶

Define the syntax for simple elements:

<xs:element name="xxx" type="yyy"/>

Here xxx refers to the name of the element, and yyy refers to the data type of the element. XML Schema has many built-in data types.

The most common types are: ¶

• Xs:string

• Xs:decimal

• Xs:integer

• Xs:boolean

• Xs:date

• Xs:time

Example ¶

Here are some XML elements:

<lastname>Refsnes</lastname>
<age>36</age>
<dateborn>1970-03-27</dateborn>

This is the corresponding simple element definition:

<xs:element name="lastname" type="xs:string"/>
<xs:element name="age" type="xs:integer"/>
<xs:element name="dateborn" type="xs:date"/>

Default values and fixed values for simple elements ¶

Simple elements can have specified default values or fixed values.

When no other value is specified, the default value is automatically assigned to the element.

In the following example, the default value is “red”:

<xs:element name="color" type="xs:string" default="red"/>

A fixed value is also automatically assigned to the element, and you cannot specify another value.

In the following example, the fixed value is “red”:

<xs:element name="color" type="xs:string" fixed="red"/>