Here is a list of all documented functions, variables, defines, enums, and typedefs with links to the documentation:

### - o -

- obj_len : saveload.cpp
- OC_END : oldloader.cpp
- OFB_FULL_LOAD : order.h
- OFB_HALT_IN_DEPOT : order.h
- OFB_NON_STOP : order.h
- OFB_PART_OF_ORDERS : order.h
- OFB_SERVICE_IF_NEEDED : order.h
- OFB_TRANSFER : order.h
- OFB_UNLOAD : order.h
- offs_base : saveload.cpp
- OffsetGroundSprite() : viewport.cpp , viewport_func.h
- OldChunkType : oldloader.cpp
- OnChange : settings_internal.h
- OnConvert : settings_internal.h
- OPENTTD_GRAPHICS_BASE_GRF_ID : newgrf_config.cpp
- OppositeCorner() : slope_func.h
- OrderClick_Delete() : order_gui.cpp
- OrderClick_FullLoad() : order_gui.cpp
- OrderClick_Goto() : order_gui.cpp
- OrderClick_Nonstop() : order_gui.cpp
- OrderClick_Refit() : order_gui.cpp
- OrderClick_Skip() : order_gui.cpp
- OrderClick_Transfer() : order_gui.cpp
- OrderClick_Unload() : order_gui.cpp
- OrderFlagMasks : order.h
- OrderGetSel() : order_gui.cpp
- ORIGINAL_BASE_YEAR : date_type.h
- ORIGINAL_MAX_YEAR : date_type.h
- OtherAxis() : direction_func.h
- OTTD2FS() : win32.cpp , stdafx.h
- OTTD_SendThreadMessage() : openttd.cpp , openttd.h
- OTTDSHGetFolderPath() : win32.h , win32.cpp
- OwnedPPPonPCP : elrail_data.h
- Owner : player_type.h
- OWNER_BEGIN : player_type.h
- OWNER_END : player_type.h
- OWNER_NONE : player_type.h
- OWNER_TOWN : player_type.h
- OWNER_WATER : player_type.h