Each feature, and each behaviour it promises, from its spec line through design, implementation and tests, by its code. A card outlined in yellow is missing a level.
No features with codes yet. Give each behaviour a spec line ending with its code, like - New sign-ups on a full event go to the waiting list. ^waitlist-1, and end the design, implementation and test lines that deal with it with [[AiSpec:PROJECT#^waitlist-1]]. Lines in this project are placed by the heading they sit under (a heading with Design, Implementation or Tests in it).