code: public int doStartTag() throws JspException {
        try {
  	SPathFilter s = new SPathFilter(new SPathParser(select).expression());
  	pageContext.setAttribute(var, s);
  	return SKIP_BODY;
        } catch (ParseException ex) {
  	throw new JspTagException(ex.toString(), ex);
        }
      }
docs: applies XPath expression from 'select' and exposes a filter as 'var'