Hi Fabio,

It looks like a bug to me that CTRL+0 sets checkbox value to .T. instead of Null. However, assigning value to Null works as expected if programmed properly. In case of InteractiveChange it requires NODEFAULT.

	PROCEDURE check1.InteractiveChange
		? PROGRAM(),this.value
		this.Value = NULL
		NODEFAULT
	ENDPROC

>If you use a checkbox with a nullable field,
>and bind this field to a checkbox,
>with CTRL+0 or set .Value to NULL not fill the field with NULL.
>
>

<snip>

--sb--