InstaGov/schema

Common

 * /post: a piece of text which can be modified

Liquid Agenda

 * /question: a decision to be made
 * /answer: a possible choice
 * /rating: ratings (votes)
 * /rating_log: log of ratings
 * /edit_log: log of everything except ratings
 * /edit_log_field: details of what changed

Debate Mapper

 * /claim

Alternatives
Much of the data structure could be handled using Semantic MediaWiki. For now, I've decided not to use that (in order to minimize platform dependence), but I keep perseverating about how useful it might be -- so here is where I will make any notes for potentially doing it that way instead (or as an alternative version of the software; no harm in having multiple implementations which might work out better in some situations):
 * /SMW