Posted to the window with the keyboard focus when a nonsystem key is released. A nonsystem key is a key that is pressed when the ALT key is not pressed, or a keyboard key that is pressed when a window has the keyboard focus.
The virtual-key code of the nonsystem key. See Virtual-Key Codes.
The repeat count, scan code, extended-key flag, context code, previous key-state flag, and transition-state flag, as shown in the following table.
Bits Meaning 0-15 The repeat count for the current message. The value is the number of times the keystroke is autorepeated as a result of the user holding down the key. The repeat count is always 1 for a WM_KEYUP message. 16-23 The scan code. The value depends on the OEM. 24 Indicates whether the key is an extended key, such as the right-hand ALT and CTRL keys that appear on an enhanced 101- or 102-key keyboard. The value is 1 if it is an extended key; otherwise, it is 0. 25-28 Reserved; do not use. 29 The context code. The value is always 0 for a WM_KEYUP message. 30 The previous key state. The value is always 1 for a WM_KEYUP message. 31 The transition state. The value is always 1 for a WM_KEYUP message.
An application should return zero if it processes this message.
For enhanced 101- and 102-key keyboards, extended keys are the right ALT and CTRL keys on the main section of the keyboard; the INS, DEL, HOME, END, PAGE UP, PAGE DOWN, and arrow keys in the clusters to the left of the numeric keypad; and the divide (/) and ENTER keys in the numeric keypad. Other keyboards may support the extended-key bit in the lParam parameter.
Applications must pass wParam to TranslateMessage without altering it at all.
Minimum supported client
|Windows 2000 Professional [desktop apps only]|
Minimum supported server
|Windows 2000 Server [desktop apps only]|
Build date: 11/16/2013