# Adding an element reference

An element reference provides a reference to a global element. A declaration that references a global element enables the referenced global element to appear in the instance document in the context of the referencing declaration.

The menu option to add an element reference only appears if there are global elements defined elsewhere in the document.

The following instructions were written for the Resource perspective, but they will also work in many other perspectives.

To add an element reference, follow these steps:

1. In the Outline view, right-click the content model you want to work with and click Add Element Ref.
2. Select the element reference.
3. In the Properties view, select the global element you want to reference in the ref list.
4. (Optional) Select the appropriate value in the MinOccurs field. This is the number of times the global element referenced may appear. If you want the element to be optional, select 0. Otherwise, select 1.
5. (Optional) Select the appropriate value in the MaxOccurs field. This is the maximum number of times the global element referenced may appear. You can select unbounded to indicate there is no maximum number of occurrences.
6. (Optional) Click the Other tab. In this page, you can specify various values for thel element reference, such as abstract, block, final, fixed/default, nillable, and substituionGroup.
7. Click the Attributes tab You can use this page to add attributes, attribute references, attributes group references, and `any` attributes to your element reference.
8. An attribute associates an attribute name with a specific type and value. To add an attribute, right-click in the Attributes page, and click Add Attribute. You can specify the following values for an attribute
   - fixed/default. Click the More button and select the Fixed or Default radio button and specify an appropriate value. If you select Fixed, the attribute has a fixed value, which cannot be changed. If you select Default, the attribute has a default value.
   - form. Use this field to indicate if the appearance of this attribute in an instance of the XML schema must be qualified by a namespace.
   - name. Enter the name of the attribute.
   - type. Click the More button and select the type of the attribute.
   - use. This field indicates how an attribute may be used in an instance document. If you select optional, the attribute may appear once, but it does not have to. If you select required, the attribute must appear once. If you select prohibited, the attribute must not appear. Note: If you selected the Default radio button, you must select optional in this field, otherwise the default value will not be valid.
9. An attribute reference provides a reference to a global attribute. To add an attribute reference, right-click in the Attributes page, and click Add Attribute Ref. A declaration that references a global attribute enables the referenced attribute to appear in the instance document in the context of the referencing declaration. The menu option to add an attribute reference only appears if there are global attributes defined elsewhere in the document.
   1. Select the reference, then select the global attribute you want it to reference from the ref drop down list.
10. An attribute group reference provides a reference to an attribute group. To add an attribute group reference, right-click in the Attributes page, and click Add Attribute Group Ref. A declaration that references an attribute group enables the referenced attribute group to appear in the instance document in the context of the referencing declaration. The menu option to add an attribute group reference only appears if there are attribute groups defined elsewhere in the document.
    1. Select the reference, then select the attribute group you want it to reference from the ref drop down list.
11. An `any` element enables attributes to appear in `any` elements. To add an `any` attribute, right-click in the Attributes page, and click Add Any Attribute. You can specify the following values for an `any` attribute:
    - For a namespace value, you can select ##any (this allows any well-formed XML from any namespace), ##local (this allows any well-formed XML that is not declared to be in a namespace, ##other (this allows any well-formed XML that is not from the target namespace of the type being defined) or ##targetNamespace (which is shorthand for the target namespace of the type being defined).
    - For a processContents value, you can select skip (the XML processor will not validate the attribute content at all), lax(the XML processor will validate the attribute content as much as it can), or strict (the XML processor will validate all the attribute content).
12. Click the Documentation tab if you want to provide any information about this element reference. The Documentation page is used for human readable material, such as a description, and the App Info page can be used to provide information for applications.

Related tasks
Adding a global element

(C) Copyright IBM Corporation 2000, 2005. All Rights Reserved.