The header file, OLE.H, contains six data structures that are of interest to an OLE server application. Three of the data structures contain single far pointers that reference corresponding VTBL structures. Each VTBL structure contains pointers to various callback functions. The following chart identifies the single-pointer structure names, the single-pointer data types, and the corresponding VTBL names:
| Single-pointer name | Single-pointer data type | VTBL |
| OLESERVER | LPOLESERVERVTBL | OLESERVERVTBL |
| OLESERVERDOC | LPOLESERVERDOCVTBL | OLESERVERDOCVTBL |
| OLEOBJECT | LPOLEOBJECTVTBL | OLEOBJECTVTBL |
The following type declarations are for the single-pointer structures (from the OLE.H include file):
typedef struct _OLESERVER
{
LPOLESERVERVTBLlpvtbl;
} OLESERVER;
typedef struct _OLESERVERDOC
{
LPOLESERVERDOCVTBLlpvtbl;
} OLESERVERDOC;
typedef struct _OLEOBJECT
{
LPOLEOBJECTVTBLlpvtbl;
} OLEOBJECT;