| DirectX SDK | 
The CONST_DDWAITVBFLAGS enumeration is used by the flags parameter of the DirectDraw7.WaitForVerticalBlank method to specify how long to wait for the vertical blank.
Enum CONST_DDWAITVBFLAGS
    DDWAITVB_BLOCKBEGIN      = 1
    DDWAITVB_BLOCKBEGINEVENT = 2
    DDWAITVB_BLOCKEND        = 4
End Enum