if (document.images) {
    buttonUp = new Image(); buttonUp.src = "images/buttonUp.jpg"; 
    buttonDown = new Image(); buttonDown.src = "images/buttonDown.jpg";
    }

    function turn_off(span) {
    if (document.images != null) {
    span.style.backgroundImage = "url('" + buttonUp.src + "')";
    }
    }

    function turn_on(span) {
    if (document.images != null) {
    span.style.backgroundImage = "url('" + buttonDown.src + "')";
    }
    }

function validate_required(field,alerttxt)
{
	with (field)
	{
		if (value==null||value=="")
  		{
			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)
{
	with (thisform)
	{
		if (validate_required(Email,"Please fill the email field")==false)
  		{
			Email.focus();
			return false;
		}
		else if (validate_email(Email,"Email address in not valid")==false)
 		{
			Email.focus();
			return false;
		}

	}
}