This structure is a movie subheader and is considered part of a movie header. The pmmTrackInfoList field of the MMMOVIEHEADER structure points to an array of these structures. The ulNumEntries field of that structure contains the number of entries in the array. It is part of the standard presentation format for movie data and is returned on mmioGetHeader and used on mmioSetHeader when the HMMIO refers to an open movie file.
typedef struct _MMTRACKINFO { ULONG ulTrackID; /* Track identifier. */ ULONG ulMediaType; /* Media type. */ ULONG ulCountry; /* Country code of track. */ ULONG ulCodePage; /* Country codepage of the track. */ ULONG ulReserved; /* Reserved. */ ULONG ulReserved2; /* Reserved. */ } MMTRACKINFO; typedef MMTRACKINFO * PMMTRACKINFO ;