THEORY: more questions

First of all, thanks for your kind explanations and input.
I have two more questions. I'm using Mark Donohue's grammar
sketch outline for my grammar and there are two terms I don't
understand: 'topic chains', and 'pivots', in the Discourse
section, where one is supposed to discuss these, anaphora,
ellipsis, and conversational structure in general.
Does anyone know what these things are? And if you know,
maybe you could also tell us what you do about them in your
own conlangs (so that my bothering questions turn out useful!).

Thanks in advance,


--Pablo Flores