nChar
Contains the character code value of the key.
nRepCnt
Contains the repeat count, the number of times the keystroke is repeated when user holds down the key.
nFlags
Contains the scan code, key-transition code, previous key state, and context code, as shown in the following list:
For IBM Enhanced 101- and 102-key keyboards, enhanced keys are the right ALT and the right 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 slash (/) and ENTER keys in the numeric keypad. Some other keyboards may support the extended-key bit in nFlags.
This method is called by the framework to allow your application to handle a Windows CE message. The parameters passed to your function reflect the parameters received by the framework when the message was received. If you call the base-class implementation of this function, that implementation will use the parameters originally passed with the message and not the parameters you supply to the function.