When you initially create a CMP entity bean, you have the option of adding persistence fields, or attributes, to the bean.
However, if you later decide that you want to add a CMP field to the entity bean and perhaps define it as a key field, you can use the EJB deployment descriptor editor. For example, if you created a CMP entity bean named Customer, you might later want to add the CMP field e-mail to the entity bean. Use the Bean page of the EJB deployment descriptor editor to add and remove CMP fields.