# Glossary

Every term in the method, in one place. Terms link to the page that treats them fully.

**Skill** — the basic building block: one concrete, precisely named ability. Either no-level or three-level. *(Chapter 2)*

**No-level skill (yes/no)** — a skill small enough that you either know it or you don't; nothing meaningful to grade. Stored internally as level 0, which is never shown to users. *(Chapter 2)*

**Three-level skill** — a skill large enough to grow through stages: beginner → confident → expert, each level a prerequisite of the next. In a tree, each level is treated as a separate skill. *(Chapter 2)*

**Beginner** — knows the basics (fresh from a course or book); can do the work but needs help or a lot of documentation along the way. *(Chapter 2)*

**Confident** — hands-on experience; delivers most tasks alone, reaching for docs only on the less common parts. *(Chapter 2)*

**Expert** — considerable experience; handles almost everything without help, looking things up only for obscure cases. Confident enough to teach others. *(Chapter 2)*

**Prerequisite** — a skill required before another becomes learnable. Defined once, on the skill itself, at organisation level — never inside a tree. *(Chapter 2)*

**No double-linking** — the rule that every dependency is expressed once, at the closest link: if B needs A and C needs B, C connects through B, never also directly to A. *(Chapters 2–3)*

**Granularity rule** — a well-cut skill takes roughly one to three months to progress one step. Longer: split it. Nothing to grade: make it no-level. In doubt: aim bigger. *(Chapter 2)*

**Tree** — a scope of view over a connected subset of skills; an area of knowledge forming a logical part of a larger whole (e.g. Testing, Frameworks). *(Chapter 3)*

**Root** — a prerequisite of a tree's skills that isn't itself in the tree; surfaces beneath the tree as its entry requirement. Derived, never placed by hand. Applies at forest level too. *(Chapter 3)*

**Forest** — a group of trees: the full scope of knowledge for a single role, usually one forest per role covering every rank. *(Chapter 4)*

**Rank** — a seniority level tied to a person (junior / mid / senior by default), defined as a concrete set of skills at given levels within a forest. *(Chapter 4)*

**Coverage** — for a skill: how many people on a team hold it, and at what level. The first team-level read. *(Chapter 8)*

**Gap** — a skill the team needs but nobody holds, or holds only at beginner. *(Chapter 8)*

**Single point of failure** — a skill exactly one person holds at a usable level; a risk the moment that person is unavailable. *(Chapter 8)*

**Skills heat map** — a grid of team members against skills, with the level in each cell; the whole forest at a glance. *(Chapter 8)*

**Skill champion** — the named person for a critical skill who answers questions, mentors, and validates self-assessments. *(Chapters 5, 8)*

**Teaching-back** — explaining or teaching a skill to someone else; the method's favourite test for advancing to confident or expert. *(Chapters 5, 7, 9)*

**Peer validation** — the practice of levels being claims that colleagues confirm, keeping assessment honest at scale — especially once levels touch pay. *(Chapter 5)*

**Forest review** — the twice-yearly session that moves skills between ranks, retires outdated skills, and adds emerged ones. One year without it is the hard maximum. *(Chapter 6)*