Returns a string that matches LDML representation of the options object.
function toLDMLString(options) {
  var getOption = getGetOption(options, 'dateformat');

  var ldmlString = '';

  var option = getOption('weekday', 'string', ['narrow', 'short', 'long']);
  ldmlString += appendToLDMLString(
      option, {narrow: 'EEEEE', short: 'EEE', long: 'EEEE'});

  option = getOption('era', 'string', ['narrow', 'short', 'long']);
  ldmlString += appendToLDMLString(
      option, {narrow: 'GGGGG', short: 'GGG', long: 'GGGG'});

  option = getOption('year', 'string', ['2-digit', 'numeric']);
  ldmlString += appendToLDMLString(option, {'2-digit': 'yy', 'numeric': 'y'});

  option = getOption('month', 'string',
                     ['2-digit', 'numeric', 'narrow', 'short', 'long']);
  ldmlString += appendToLDMLString(option, {'2-digit': 'MM', 'numeric': 'M',
          'narrow': 'MMMMM', 'short': 'MMM', 'long': 'MMMM'});

  option = getOption('day', 'string', ['2-digit', 'numeric']);
  ldmlString += appendToLDMLString(
      option, {'2-digit': 'dd', 'numeric': 'd'});

  var hr12 = getOption('hour12', 'boolean');
  option = getOption('hour', 'string', ['2-digit', 'numeric']);
  if (IS_UNDEFINED(hr12)) {
    ldmlString += appendToLDMLString(option, {'2-digit': 'jj', 'numeric': 'j'});
  } else if (hr12 === true) {
    ldmlString += appendToLDMLString(option, {'2-digit': 'hh', 'numeric': 'h'});
  } else {
    ldmlString += appendToLDMLString(option, {'2-digit': 'HH', 'numeric': 'H'});
  }

  option = getOption('minute', 'string', ['2-digit', 'numeric']);
  ldmlString += appendToLDMLString(option, {'2-digit': 'mm', 'numeric': 'm'});

  option = getOption('second', 'string', ['2-digit', 'numeric']);
  ldmlString += appendToLDMLString(option, {'2-digit': 'ss', 'numeric': 's'});

  option = getOption('timeZoneName', 'string', ['short', 'long']);
  ldmlString += appendToLDMLString(option, {short: 'z', long: 'zzzz'});

  return ldmlString;
}