Opening the Schema Editor
To open the schema editor:

In the pop-up menu of the namespace you just created, select
Schema.
The XML schema editor opens. By default, it displays the "Standard level" and filters a certain number of characteristics.
To access the advanced functionalities required for the construction of XML schemas:

In the schema editor, click the
Tools menu and select
XML Expertise Level.
Specifying the URN for a Namespace
To specify the URN for a namespace:
1. In the schema editor navigator, click the namespace.
2. In the right part of the editor, select the tab for the generation language you are using and enter the URN for the package in the [XDD] urn box.