There are seven indicators as follows:

Order indicators:

• All
• Sequence
• Choice

Occurrence indicators:

• maxOccurs
• minOccurs

Group indicators:

• Group name
• attributeGroup name

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

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

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 only(the <minOccurs> and <maxOccurs> are described later

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

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

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

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

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

The example above indicate 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.

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

The example above indicate 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 as given in the following example:

An XML file named "Myfamily.xml":

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

Here is the schema file called "family.xsd":

Group indicators are used to define related set of elements.

Element groups are defined with the group declaration as follows:

You must define an all, choice, or sequence elements 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:

After you have defined a group, you can reference it in another definition as follows:

Attribute groups are defined with the attributeGroup declaration as follows :

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

After you have defined an attribute group, you can reference it in another definition as follows: