var validChars = 'abcdefghijklmnopqrstuvwxyz0123456789.@-() ';

function checkValidChars(val)
{
	var returnVal = true;
	for(i=0; i<val.length; i++)
	{
		if(validChars.indexOf(val.charAt(i).toLowerCase()) < 0)
		{
			alert('invalid characters used. Try using only ' + validChars);
			returnVal = false;
			break;
		}
	}
	return returnVal;
}

function validateFormValue(val, label)
{
	if( val == '' || val == 0)
	{
		alert(label + ' required');
		return false;
	}
	else
	{
		return checkValidChars(val);
	}
}