Editors for Deployment Descriptors 
Purpose
Enterprise Application, Web Module, and EJB Module projects (and their respective archive files: EAR, WAR, and JAR) contain deployment descriptors. These are automatically generated when the projects are created and when they are modified. With the multipage editors, you can display them and also edit them manually. For more information, see:
Features
The tabs of the multipage editors are organized to reflect the structure of the respective deployment descriptors.
By using the tabs to edit the deployment descriptors, you ensure that the XML code is created correctly. For example, the tags will be nested correctly in the XML source code.
The Source tab allows you to display the source XML. You can directly edit the XML code but we recommend you use the forms in the multipage editor. You can customize the formatting and colors of the displayed XML code (Window ® Preferences ® Web Editors ® XML/HTML Editor).