Three types of indicators

http://www.google.com/webhp?source=search_app#hl=en&gs_rn=11&gs_ri=psy-ab&gs_mss=Ciboney.%20&suggest=p&pq=ciboney.%20&cp=18&gs_id=q&xhr=t&q=types+of+indicators&es_nrs=true&pf=p&sclient=psy-ab&oq=ypes+of+indicators&gs_l=&pbx=1&bav=on.2,or.r_qf.&fp=1a317f44bff72960&biw=711&bih=453