Are non-binding promises and deals allowed in Oath, and what makes a promise binding?

Question

Accepted Answer

Yes. Players may negotiate and promise anything, but the game enforces only promises made through powers that say 'binding' (such as the Tribunal) and Citizenship offers. Other promises rest on the players' word, and no deal can override the game's rules or move resources a card doesn't allow.

Oath: Chronicles of Empire & Exile

Are non-binding promises and deals allowed in Oath, and what makes a promise binding?