The file object content for JSPs is based on a special template called DefaultContent defined with respect to the FileObject metaclass. It is located in the Profile/FileObject/Criteria/JSP/Templates category of the Java object language. This link to the template exists as a basis, therefore if you edit the file object, the link to the template is lost - the mechanism is similar to that of operation default bodies.
For more information on the Criteria category, see "Criteria (Profile)" in the Extending your Models with Profiles chapter of the Customizing and Extending PowerDesigner manual.
Java Server Page files are identified using the JSPFile stereotype. The server page name is synchronized with the JSP component name following the convention specified in the Value box of the Settings/Namings/JSPFileName entry of the Java object language.
You can right-click a file object, and select Open With→ text editor from the contextual menu to display the content of the file object.