function checkall(form,pattern,type)
{
  for(i=0;i<document.forms[form].elements.length;++i)
    {
      elm=document.forms[form].elements[i];
      
      if(elm.type=='checkbox' 
          && elm.name.match(new RegExp(pattern)))
        {
          switch(type)
            {
              case 'check':
                attr=true;
                  break;
              case 'uncheck':
                attr=false;
                  break;
              case 'toggle':
                attr=(elm.checked)?false:true;
                  break;
            }
          elm.checked=attr;
        }
    }
}