Generally we need to show one or more fields from a model that is related to another model used in CGridView.
For our case we will use two related models, which explain how to use model "A" fields in a CGridView that used model "B".
Clearing CGridView filters and sort orders from the web pages, is usefull for the end user. Yii does not seem to propose a standard method. Furthermore, this is especially usefull when filters are "remembered" in the user's session.