You define a VB .NET namespace using a package.
PowerDesigner models namespaces as standard packages with the Use Parent Namespace property deselected.
In the following example, class Architect is declared in package Design which is a sub-package of Factory. The namespace declaration is the following:
Namespace Factory.Design Public Class Architect ... ...End Class End Namespace ' Factory.Design
Classifiers defined directly at the model level fall into the VB .NET global namespace.