Last modified: July 23, 2011

Applies to: Outlook

Describes a GUID structure used to describe an identifier for a MAPI interface.

typedef struct _GUID
  unsigned long Data1;
  unsigned short Data2;
  unsigned short Data3;
  unsigned char Data4[8];

See the GUID structure.

An IID structure is used to uniquely identify a MAPI interface and to associate a particular interface with an object. For example, when a client calls IMAPISession::OpenEntry to open a folder, the client sets the lpInterface parameter to point to an IID representing the IMAPIFolder interface. MAPI defines the IMAPIFolderIID to be IID_IMAPIFolder. IID structures are also used to uniquely identify OLE interfaces.

All of the specific IID structures for the MAPI interfaces are defined in the Mapiguid.h header file.