Update from Glyn, page-288

Agree. Official docs are legally binding.
Further any interpretation ambiguities would call into question clarifications preceding acceptance including questions raised at official meetings. Coupled in with that is a determination of intent, and previous docs and statements could be used to clarify.
If indeed other items were included, that would be a legal field day that no end of ambiguous replies could cover.

Given the preponderance of mails to Obj with the ambiguous replies, it could be posited this question requires formal clarification especially since relates directly to remuneration. Better to clear up now - the bonuses are not chicken feed and would be worth at least a few days and lines to formalise the revenue definition.