global with sharing class CustomFieldsService
This class provides functionality related to custom fields which are displayed on the enhanced UI.
global with sharing class Field
This class wraps the field path and value of a custom field on a record. This class is marked as serializable and deserializable to work around an issue in enforcing JsonAccess for Visualforce remoting requests. Warning: Do not rely on any behavior available via serializing as or deserializing from JSON that is not part of the global API because it might be subject to change.