> > But I have yet to see an answer to my question, which I am asking
> > now for the third time:
> > what is there in this form that makes sequence a
> > *necessary* and *inherent* property of it, and why?
>
> i will answer again: it is an inherent property due to its existence,
> an existence in complementary distribution of the semantic TAM with [x-]
> qatal.
> languages do not develop/preserve two verb systems in order to mark the
> same tense-and/or-aspect-and/or-mood or to 'mark' word order!
> however, languages do have special narrative, mainline and sequential
> forms.
Since this really doesn't say anything in response to my question,
it's difficult to know how to respond. "It's there because it's there"
does very little to advance the discussion. For further info, see
Peter's response.