| Horde_OpenXchange_Base | Horde_OpenXchange_Base is the base class for HTTP API requests to an Open-Xchange server. |
| Horde_OpenXchange_Contacts | Horde_OpenXchange_Contacts is the interface class for the contacts storage of an Open-Xchange server. |
| Horde_OpenXchange_Events | Horde_OpenXchange_Events is the interface class for the events storage of an Open-Xchange server. |
| Horde_OpenXchange_EventsAndTasks | Horde_OpenXchange_EventsAndTasks is the base class for the events and tasks storage of an Open-Xchange server. |
| Horde_OpenXchange_Exception | Base exception class for Horde_OpenXchange. |
| Horde_OpenXchange_Tasks | Horde_OpenXchange_Tasks is the interface class for the tasks storage of an Open-Xchange server. |