XML Schema Indicators

## Schema Tutorial

XSD HOME XSD Intro XSD Why Use XSD How To XSD <schema>

## Simple Types

XSD Elements XSD Attributes XSD Restrictions

## Complex Types

XSD Elements XSD Empty XSD Elements Only XSD Text Only XSD Mixed XSD Indicators XSD <any> XSD <anyAttribute> XSD Substitution XSD Example

## Data Types

XSD String XSD Date XSD Numeric XSD Misc

## Schema References

XSD Editor XSD Reference XSD Validator

# XSD Indicators

« Previous
Next Chapter »

We can control HOW elements are to be used in documents with indicators.

## Indicators

There are seven indicators:

Order indicators:

- All
- Choice
- Sequence

Occurrence indicators:

- maxOccurs
- minOccurs

Group indicators:

- Group name
- attributeGroup name

## Order Indicators

Order indicators are used to define the order of the elements.

### All Indicator

The <all> indicator specifies that the child elements can appear in any order, and that each child element must occur only once:

<xs:element name="person">
<xs:complexType>
<xs:all>
<xs:element name="firstname" type="xs:string"/>
<xs:element name="lastname" type="xs:string"/>
</xs:all>
</xs:complexType>
</xs:element>

Note: When using the <all> indicator you can set the <minOccurs> indicator to 0 or 1 and the <maxOccurs> indicator can only be set to 1 (the <minOccurs> and <maxOccurs> are described later).

### Choice Indicator

The <choice> indicator specifies that either one child element or another can occur:

<xs:element name="person">
<xs:complexType>
<xs:choice>
<xs:element name="employee" type="employee"/>
<xs:element name="member" type="member"/>
</xs:choice>
</xs:complexType>
</xs:element>

### Sequence Indicator

The <sequence> indicator specifies that the child elements must appear in a specific order:

<xs:element name="person">
<xs:complexType>
<xs:sequence>
<xs:element name="firstname" type="xs:string"/>
<xs:element name="lastname" type="xs:string"/>
</xs:sequence>
</xs:complexType>
</xs:element>

## Occurrence Indicators

Occurrence indicators are used to define how often an element can occur.

Note: For all "Order" and "Group" indicators (any, all, choice, sequence, group name, and group reference) the default value for maxOccurs and minOccurs is 1.

### maxOccurs Indicator

The <maxOccurs> indicator specifies the maximum number of times an element can occur:

<xs:element name="person">
<xs:complexType>
<xs:sequence>
<xs:element name="full_name" type="xs:string"/>
<xs:element name="child_name" type="xs:string" maxOccurs="10"/>
</xs:sequence>
</xs:complexType>
</xs:element>

The example above indicates that the "child_name" element can occur a minimum of one time (the default value for minOccurs is 1) and a maximum of ten times in the "person" element.

### minOccurs Indicator

The <minOccurs> indicator specifies the minimum number of times an element can occur:

<xs:element name="person">
<xs:complexType>
<xs:sequence>
<xs:element name="full_name" type="xs:string"/>
<xs:element name="child_name" type="xs:string"
maxOccurs="10" minOccurs="0"/>
</xs:sequence>
</xs:complexType>
</xs:element>

The example above indicates that the "child_name" element can occur a minimum of zero times and a maximum of ten times in the "person" element.

Tip: To allow an element to appear an unlimited number of times, use the maxOccurs="unbounded" statement:

A working example:

An XML file called "Myfamily.xml":

<?xml version="1.0" encoding="ISO-8859-1"?>
<persons xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="family.xsd">
<person>
<full_name>Hege Refsnes</full_name>
<child_name>Cecilie</child_name>
</person>
<person>
<full_name>Tove Refsnes</full_name>
<child_name>Hege</child_name>
<child_name>Stale</child_name>
<child_name>Jim</child_name>
<child_name>Borge</child_name>
</person>
<person>
<full_name>Stale Refsnes</full_name>
</person>
</persons>

The XML file above contains a root element named "persons". Inside this root element we have defined three "person" elements. Each "person" element must contain a "full_name" element and it can contain up to five "child_name" elements.

Here is the schema file "family.xsd":

<?xml version="1.0" encoding="ISO-8859-1"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
elementFormDefault="qualified">
<xs:element name="persons">
<xs:complexType>
<xs:sequence>
<xs:element name="person" maxOccurs="unbounded">
<xs:complexType>
<xs:sequence>
<xs:element name="full_name" type="xs:string"/>
<xs:element name="child_name" type="xs:string"
minOccurs="0" maxOccurs="5"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>

## Group Indicators

Group indicators are used to define related sets of elements.

### Element Groups

Element groups are defined with the group declaration, like this:

<xs:group name="groupname">
...
</xs:group>

You must define an all, choice, or sequence element inside the group declaration. The following example defines a group named "persongroup", that defines a group of elements that must occur in an exact sequence:

<xs:group name="persongroup">
<xs:sequence>
<xs:element name="firstname" type="xs:string"/>
<xs:element name="lastname" type="xs:string"/>
<xs:element name="birthday" type="xs:date"/>
</xs:sequence>
</xs:group>

After you have defined a group, you can reference it in another definition, like this:

<xs:group name="persongroup">
<xs:sequence>
<xs:element name="firstname" type="xs:string"/>
<xs:element name="lastname" type="xs:string"/>
<xs:element name="birthday" type="xs:date"/>
</xs:sequence>
</xs:group>
<xs:element name="person" type="personinfo"/>
<xs:complexType name="personinfo">
<xs:sequence>
<xs:group ref="persongroup"/>
<xs:element name="country" type="xs:string"/>
</xs:sequence>
</xs:complexType>

### Attribute Groups

Attribute groups are defined with the attributeGroup declaration, like this:

<xs:attributeGroup name="groupname">
...
</xs:attributeGroup>

The following example defines an attribute group named "personattrgroup":

<xs:attributeGroup name="personattrgroup">
<xs:attribute name="firstname" type="xs:string"/>
<xs:attribute name="lastname" type="xs:string"/>
<xs:attribute name="birthday" type="xs:date"/>
</xs:attributeGroup>

After you have defined an attribute group, you can reference it in another definition, like this:

<xs:attributeGroup name="personattrgroup">
<xs:attribute name="firstname" type="xs:string"/>
<xs:attribute name="lastname" type="xs:string"/>
<xs:attribute name="birthday" type="xs:date"/>
</xs:attributeGroup>
<xs:element name="person">
<xs:complexType>
<xs:attributeGroup ref="personattrgroup"/>
</xs:complexType>
</xs:element>
« Previous
Next Chapter »

## Your suggestion:

Your E-mail (optional):

Page address:

Description:

Close [X]

## Thank You For Helping Us!

Your message has been sent to W3Schools.

Close [X]
Search w3schools.com:

## WEB HOSTING

Best Web Hosting UK Reseller Hosting Wow! $5 SSD Hosting

## WEB BUILDING

Download XML Editor
FREE Website BUILDER FREE Website Creator

## WEB RESOURCES

Web Statistics Web Validation

## SHARE THIS PAGE