function unCheckAll() 
 { 
  self.document.forms[1].ids.value = "";
  for (i=0;i<self.document.forms[1].elements.length;i++) 
  { 
   if (self.document.forms[1].elements[i].type == "checkbox" && self.document.forms[1].elements[i].checked) 
   { 
    self.document.forms[1].elements[i].checked = false; 
   } 
  } 
 }
 function onCheck(checkbox)
 {
  var i,id;
  id = checkbox.name.split('_');
  id = id[1];
  if (!checkbox.checked) 
  {
   arrayIDs = self.document.forms[1].ids.value.split(';');
   self.document.forms[1].ids.value = "";
   for (i=0; i < arrayIDs.length; i++) 
   {
    if (arrayIDs[i] != id) 
    {
     if (self.document.forms[1].ids.value=="") {self.document.forms[1].ids.value=arrayIDs[i];} else {self.document.forms[1].ids.value=self.document.forms[1].ids.value+';'+arrayIDs[i];}
    }
   }
  } else {if (self.document.forms[1].ids.value=="") {self.document.forms[1].ids.value=id;} else {self.document.forms[1].ids.value=self.document.forms[1].ids.value+';'+id;}}
 }

 function onSubmit()
 {
  if(self.document.forms[1].ids.value=="")
  {
   alert('Выберите песню');
   return false;
  }
  return true;
 }