function checkbox(chkbox, lblTxt) {
  var lbl = document.getElementById(lblTxt);
  if(lbl != null) {
    if(chkbox.checked) {
      lbl.className = 'selected';
    }
    else {
      lbl.className = '';
    }
  }
}


function validate_required(field,currentPrompt,alerttxt) {
  with (field) {
    if (value==null||value==""||value==currentPrompt)
      {alert(alerttxt);return false;}
    else {return true;}
  }
}
function validate_email(field,alerttxt){
  with (field) {
    apos=value.indexOf("@");
    dotpos=value.lastIndexOf(".");
    if (apos<1||dotpos-apos<2) 
      {alert(alerttxt);return false;}
    else {return true;}
  }
}
  
function validate_form(thisform)
{
	debugger
	
	var test = thisform;
		
	var pre = preval.split('_');
	var preval = pre[0] + "_" + pre[1] + "_";
	
	var name = document.getElementById(preval + 'name');
	var phone = document.getElementById(preval + 'phone');
	var email = document.getElementById(preval + 'email');
	
	
	preval
	
  with (thisform) {
    if (validate_required(name,"Name","Please enter your name")==false) 
      {name.focus();return false;}
    if (validate_required(phone,"Telephone Number","Please enter a contact number")==false) 
      {phone.focus();return false;}
    if (validate_required(email,"Email Address","Please enter your email address")==false)
      {email.focus();return false;}
    if (validate_email(email,"Your email address does not appear to be valid, please try again")==false)
      {email.focus();return false;}
  }
}