A note to the Peirce list
Seems to me that in a triad you are acknowledging that it is a unity and that everything in it is subsumed to the point that such things as subject and object are if there at all blurred. The object of a triad might be seen as an expression, an action or both, following the Pragmatic Maxim — the entire consideration. So you might have a sign which is sort of a subject and an index which is sort of a colander through which to strain your thoughts and when they reach the symbol stage they have morphed into the object which was not there until now as it were. I am not sure grammatical acuity is possible in this context. But then again what do I know.