@classmethod
def getSpecific(class_, tool, css, js):
    """Returns a chunk of XHTML code for including p_css and p_js files
           specifically required by some fields."""
    r = []
    if css:
        for url in css:
            r.append(class_.css(class_.getUrl(url, tool)))
    if js:
        for url in js:
            r.append(class_.js(class_.getUrl(url, tool)))
    return '\n'.join(r)
