What is the usefulness of the following?
<ui:composition template="template.xhtml">;
"In a template client page using <ui:composition>, anything outside of the bounds of a  tag is ignored and is not included in the rendered output" (JavaServerFaces 2.0, the complete reference, pg.61)
Since everything outside <ui:define> is ignored, why put anything there? Nothing has to be put outside the <ui:define>.
But doing so, all I get will be the template itself with only some "variable" parts filled.
It seems not to be this big deal. Another thing I don't understand, is that template attribute of composition element is optional. What does it represent a template client without the reference to a template?
 
     
     
    