Theoretical linguistics offers detailed ways of thinking about structure, interpretation, and the relationship between language and thought. We study these ideas in their own right and investigate how they can inform Symbolic SI. The broader research direction is Syntactic Intelligence, with the same Syntactic Engine working across five levels and in both comprehension and generation. Developing the representations and RuleBases needed for that direction is continuing work. Our public work proceeds through software, specifications, explanations, and worked examples. The aim is to make each step concrete enough to examine and discuss.