function blocking(a){if(document.layers){current=(document.layers[a].display=='block')?'none':'block';document.layers[a].display=current}else if(document.all){current=(document.all[a].style.display=='block')?'none':'block';document.all[a].style.display=current}else if(document.getElementById){vista=(document.getElementById(a).style.display=='block')?'none':'block';document.getElementById(a).style.display=vista}}