JSP programming best practice: Use the .jspf extension for JSP segments
A JSP page can consist of one or more files: for example, the file containing a top-level JSP page, several files containing dynamically included JSP pages, and several files containing statically included JSP segments. Unlike the top-level or dynamically included pages, JSP segments need not be legal JSP pages and thus may not compile properly.
To enable code development and support tools, such as the WebSphere Commerce JSP batch compiler, to differentiate between the two types of files, use the .jsp extension for the source files of complete JSP pages and use the .jspf extension for the source files of JSP segments.