function isNum(sText){	
	var ValidChars = "0123456789.";
	var IsNumber=true;
	var Char;

	for (i = 0; i < sText.length && IsNumber == true; i++) { 
		Char = sText.charAt(i); 
		if (ValidChars.indexOf(Char) == -1) {
			IsNumber = false;
		}
	}
	return IsNumber;   
}
function validateFeedback(){
	var noError = true;
	var errMsg = "The following errors occurred:\n";

	if (document.feedbackForm.name.value == ""){
		noError = false;
		errMsg += "- Name cannot be empty\n";
	}
	
	if (document.feedbackForm.tel.value == ""){
		noError = false;
		errMsg += "- Tel cannot be empty\n";
	}
	else if (!isNum(document.feedbackForm.tel.value)){
		noError = false;
		errMsg += "- Tel must be numeric\n";
	}
	
	if (document.feedbackForm.email.value == ""){
		noError = false;
		errMsg += "- Email cannot be empty\n";
	}
	else if (document.feedbackForm.email.value.indexOf ("@") == -1){
		noError = false;
		errMsg += "- Invalid Email address\n";
	}
	
	if (document.feedbackForm.comments.value == ""){
		noError = false;
		errMsg += "- Comments cannot be empty\n";
	}
	
	if (!noError){
		alert (errMsg);
	}
	
	return noError;
}
				
function show_hide(the_layer)
{
  if(document.getElementById(the_layer))
  {
    if(document.getElementById(the_layer).style.display == 'none')
    {
      document.getElementById(the_layer).style.display = 'inline';
    }
    else
    {
      document.getElementById(the_layer).style.display = 'none';
    }
  }
}