Specifies various aspects of a keystroke. This member can be certain combinations of the following values. KEYEVENTF_EXTENDEDKEY - If specified, the scan code was preceded by a prefix byte that has the value 0xE0 (224). KEYEVENTF_KEYUP - If specified, the key is being released. If not specified, the key is being pressed. KEYEVENTF_SCANCODE - If specified, wScan identifies the key and wVk is ignored. KEYEVENTF_UNICODE - Windows 2000/XP: If specified, the system synthesizes a VK_PACKET keystroke. The wVk parameter must be zero. This flag can only be combined with the KEYEVENTF_KEYUP flag. For more information, see the Remarks section.