Several multimedia file I/O functions use the MMCKINFO structure to specify and retrieve information about RIFF chunks. The MMSYSTEM.H header file defines the MMCKINFO structure as follows:
typedef struct _MMCKINFO
{
FOURCC ckid; // chunk ID
DWORD cksize; // chunk size
FOURCC fccType; // form type or list type
DWORD dwDataOffset; // offset of data portion of chunk
DWORD dwFlags; // flags
} MMCKINFO;