The DIDEVCAPS structure is defined as :-

struct DIDEVCAPS {
DWORD dwSize;
DWORD dwFlags;
DWORD dwDevType;
DWORD dwAxes;
DWORD dwButtons;
DWORD dwPOVs;
DWORD dwFFSamplePeriod;
DWORD dwFFMinTimeResolution;
DWORD dwFirmwareRevision;
DWORD dwHardwareRevision;
DWORD dwFFDriverVersion;
};