Let say that you want to prevent the user from typing the letter "A" in a textbox. You would write the following code in the textbox KeyPress() event:

IF Upper(Chr(nKeyCode)) = "A"
	NODEFAULT
ENDIF

If you did not include NODEFAULT in the IF block, VFP would have executed it's default behaviour and a key press and would have displayed the character "A" in that case.

HTH

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>I have notice the nodefault option in define class command, what the 'nodefault' affect? I don't understand what the MSDN library say.