The DMUS_IO_TIMESIGNATURE_ITEM structure contains information about a time signature change. It is used in the Time Signature Track Chunk.
typedef struct _DMUS_IO_TIMESIGNATURE_ITEM {
    MUSIC_TIME  mtTime;
    BYTE        bBeatsPerMeasure;
    BYTE        bBeat;
    WORD        wGridsPerBeat;
} DMUS_IO_TIMESIGNATURE_ITEM;
   Windows NT/2000: Requires Windows 2000.
  Windows 95/98: Requires Windows 95 or later. Available as a redistributable for Windows 95.
  Header: Declared in dmusicf.h.