Hi Sergey

Thanks for your replies.

>Neither _True nor IsTrue will be affected by above #DEFINE because VFP replaces the whole words only. Anyway, I would go with Craig suggestion elsewhere in this thread.

That is a relief. So I guess I can safely stick to _True as opposed to IsTrue() as below:

#define True .T.

IF _True(xx)
   ...
ENDIF

IF NOT _True(xx)
   ...
ENDIF

as opposed to

IF IsTrue(xx)
   ...
ENDIF

IF NOT IsTrue(xx)
   ...
ENDIF