A TemplateParameter references aParameterableElement that is exposed as a formal template parameter in the containing template. This parameterable element is meaningful only within the template, or other templates that may have access to its internals (e.g. if the template supports specialization). The exposed parameterable element may not be used in other parts of the model. A TemplateParameter may own the exposed ParameterableElement in situations where that element is only referenced from within the template.