Reading the Map · Reference
Every bold term from the book, defined. Each entry gives the plain-English translation first — what it actually means — followed by a one-line note on why it matters or when it comes up. Where a term has a formal source, it is named. Alphabetical.
A
ADM (Architecture Development Method) — TOGAF’s cycle of phases for developing an enterprise architecture, from vision through to governance. The method most organisations borrow from, ideally used selectively rather than run in full as ritual.
Advisory function — an architecture body that offers expert opinion others may take or leave, as opposed to a design authority that decides. The distinction matters because an advisory body dressed in design-authority language produces governance theatre.
Application architecture — the view of the software estate: what systems exist, what they do, and how they connect. The BDAT layer where most IT investment and most accumulated debt live.
Application portfolio — a structured, assessed catalogue of the applications an organisation depends on, mapped to capabilities. The instrument that makes the application estate visible and governable; most organisations have a licence register, not a portfolio.
Architecture Building Block (ABB) — a required capability described in solution-neutral terms — what is needed, before what implements it. Specified before the Solution Building Block; reversing the order corrupts the requirement.
Architecture debt — the accumulated cost of structural decisions that constrain future options, living between systems rather than inside them. More dangerous than technical debt: wider scope, lower visibility, poorer reversibility. Must be translated into financial consequence to be acted on.
Architecture governance — the practice of ensuring that decisions made for the whole are honoured by the parts. Makes good analysis stick; its instrument is the Architecture Review Board.
Architecture principle — an agreed commitment that guides architectural decisions (e.g. “cloud-first”, “single patient identity”). Rules with a why; transmitting the why is what makes them followed rather than evaded.
Architecture Review Board (ARB) — the standing body that exercises architecture governance. Works only with a clear threshold, real authority, and honesty about whether it decides or merely advises.
Architecture roadmap — the ordered sequence of changes that moves an estate from current to target state, with transition states. Not a project plan; answers “what, in what order, and why”, not “what tasks by when”.
Architecture Theatre — governance that looks rigorous but produces nothing binding. Recognisable by its inability to name a single decision it has prevented or reversed.
Architecture Vision — a short, agreed statement of what a piece of architectural work is for: problem, stakeholders, scope, success, constraints, risks, approach. TOGAF Phase A; the cheapest phase and the most expensive to skip.
ArchiMate — the standard visual notation for enterprise architecture, showing business, application, and technology layers and their relationships. Its signature value is the vertical trace from a business need down to its infrastructure.
B
Baseline (current state) — the documented architecture as it actually is. Document it to the level of detail the decision requires, and no more — resist the pull to completeness.
BDAT — the four architecture domains: Business, Data, Application, Technology. The standard decomposition; each domain is a different view of the same enterprise.
Business architecture — how the organisation is structured to do its work: capabilities, processes, value streams. The top BDAT layer; what the organisation does, independent of the technology.
BIZBOK — the Business Architecture Body of Knowledge, the reference for business architecture practice. The domain framework for the business layer, including capability mapping.
Building block — a reusable component of an architecture, defined once and used in many places. Comes in two kinds: Architecture Building Blocks (what is needed) and Solution Building Blocks (what implements it).
C
Capability — a stable ability the organisation must have, independent of how or who delivers it (e.g. “manage patient records”). The right unit of analysis because capabilities change slowly, outlasting reorganisations and process changes.
Capability map — a structured picture of what an organisation does, organised into levels. Read at board altitude (Level 1) or programme altitude (Level 3); becomes a decision tool when heat-mapped.
COBIT — the framework for governing an enterprise’s use of IT. Sits downstream of architecture; the control environment, often invoked at audit time.
Component diagram — a diagram of systems, their interfaces, and their dependencies. Read for fragility (single points of failure, cycles) and, crucially, for what has been left out.
Cost of inaction — the quantified, growing cost of not addressing a problem. The phrase that unlocks budget by reframing a discretionary improvement as a non-discretionary cost already being incurred.
Current state — see Baseline.
D
Data architecture — how information is defined, owned, mastered, and made trustworthy. The BDAT domain everyone underestimates; ownership and master data are its hardest questions.
Data owner — the person accountable for whether a data entity is correct and trustworthy. An unowned data entity is a problem nobody is fixing; ownership voids are where data quality dies.
Decision authority / design authority — a body that makes binding architectural decisions, as opposed to one that only advises. “No” must mean no, or it is not a design authority.
Decision latency — the gap between when a decision could be made and when it is, and the cost of that gap. Deferring a decision is itself a decision with a price, paid in money, risk, and forgone opportunity.
Dependency — a relationship in which one thing requires another to function. Reading dependency direction tells you the blast radius of a failure; hidden dependencies wreck migration plans.
E
Enterprise architect — the role holding the broadest, longest view of the estate and its relationship to strategy. The most senior and abstract architecture role; risks losing touch with delivery.
Enterprise architecture (EA) — the discipline of seeing and shaping the whole technology estate so the parts serve the organisation rather than fragment it. A way of thinking — system-seeing, consequence-tracing — as much as a job title.
Event-driven — an architecture pattern where systems react to events rather than calling each other directly. Decouples systems and scales well; fails by becoming hard to trace and debug.
G
Gap analysis — the disciplined identification of the differences between current and target state, categorised and prioritised. Its key insight: the most important gaps (enablers) are rarely the most obvious ones (visible problems).
Governance — see Architecture governance.
H
Heat map — a capability map coloured to show health (red/amber/green) against importance and performance. The colours name business-level symptoms, not technical causes; reading red as “replace the system” is the classic error.
Horizon — a time band on a roadmap, less precise the further out it goes. Near horizons are concrete and costed; far horizons are directional and honestly vague.
Hub-and-spoke — an integration pattern where systems connect through a central hub rather than to each other. Collapses the connection count; fails by making the hub a critical single point.
Human-machine boundary — within an AI-augmented capability, the designed division between machine judgement and human judgement. Where accountability is designed in or accidentally lost; the central question of the People-Process-Technology-AI model.
I
Integration architecture — the description of how applications connect: what data flows, by what mechanism, with what error handling. The integration map reveals the estate’s fragility, especially its point-to-point connections.
Intent gap — the distance between what was intended and what was understood, as meaning is lost through organisational handoffs. Dooher’s central concept; closed by teaching the why, not just policing the what.
ITIL — the framework for IT service management — running what architecture builds. Often the most consistently practised framework in an organisation, and rarely thought of as architecture.
M
Master data — the single authoritative version of a key data entity (e.g. patient identity). Its absence forces every system to build its own version, the deepest kind of data debt.
Microservices — an architecture pattern decomposing an application into many small, independently deployable services. Buys flexibility; fails by operational sprawl and distributed complexity.
P
Pattern — a named, recurring shape of solution with documented consequences and failure modes. Recognising a pattern imports the experience of everyone who met it before; naming a pattern is diagnosing its risk.
People-Process-Technology (PPT) — the traditional triad for designing capabilities. Davis argues AI breaks it, requiring a fourth element: People-Process-Technology-AI.
Point-to-point integration — systems wired directly to each other rather than through a shared platform. Simple per connection, disastrous in aggregate; fails by unmanageable proliferation and silent breakage.
Portfolio — see Application portfolio.
R
Rationalisation — the programme of decommissioning, consolidating, and remediating an application estate based on the portfolio assessment. Hard not because the answer is unclear but because executing it requires governance with authority.
6R model — the six dispositions for an application: Retire, Retain, Rehost, Replatform, Repurchase, Refactor. Turns the portfolio assessment from diagnosis into committed decision.
Refactor — re-architect an application significantly to remove debt and fit the target. The most expensive 6R disposition; reserved for strategic capabilities with no commercial alternative.
Rehost (lift-and-shift) — move an application to new infrastructure unchanged. Fast and low-risk; carries the application’s debt forward intact.
Repurchase — replace an application with a different product, typically SaaS. Right when the capability is a commodity the organisation has no reason to run itself.
Replatform — move an application with modest changes to exploit the new environment. Between rehost and refactor in cost and benefit.
Retain — keep an application unchanged, as an active decision with a review date. Legitimate, but passive retention is how estates ossify.
Retire — decommission an application. The most-identified and least-executed disposition, because every retirement has a constituency.
S
SABSA — the framework for security architecture, tracing security controls to business risk. The domain framework for security; often absent, leaving security as a compliance checklist.
Sequence diagram — a diagram of messages between participants over time, read top to bottom. The most powerful artefact for surfacing failure, because it represents time and therefore failure-in-time.
Solution Building Block (SBB) — the specific product or technology selected to fulfil an Architecture Building Block. Selected after the ABB is defined; selecting it first corrupts the requirement.
Strategic capability — the connection of a technical investment to an ability the organisation has decided matters. One of the phrases that unlocks budget, by reframing spend from housekeeping to strategy.
Solution architect — the role translating enterprise direction into a workable design for a specific programme. Closest to delivery; the connective tissue between the enterprise view and the teams building.
T
Target state — the documented architecture as the organisation intends it to become. Usually contested, because different stakeholders want different futures; the architect’s job is to make the trade-offs explicit.
Technical debt — the accumulated cost of implementation shortcuts, living inside systems. Distinct from architecture debt, which lives between systems and is harder to reverse.
Technology architecture — the infrastructure and platforms applications run on. The foundation BDAT layer; Meridian’s VMware crisis is a technology-architecture event with estate-wide consequences.
TOGAF — The Open Group Architecture Framework, the most widely used EA method framework. Provides the ADM; most valuable used selectively as a thinking structure rather than performed in full.
Transition architecture (transition state) — a defined, stable, survivable intermediate configuration between current and target state. Designed for safety rather than elegance, because organisations live in their transition states for months or years.
V
Value chain — on a Wardley map, the chain of needs from the visible user need down to the invisible foundations. The vertical axis of a Wardley map; height means closer to the user need.
W
Wardley map — a strategy diagram plotting components by position in the value chain (vertical) and evolutionary stage (horizontal). The one architecture diagram about the future; shows what is commoditising and where to invest effort.
Wave — a coherent bundle of related change on a roadmap that moves the architecture between stable states. Distinguishes a roadmap (a sequence of states) from a backlog (a list).
Z
Zachman Framework — a classification grid of six interrogatives crossed with six perspectives (36 cells), each a distinct kind of description. Not a method; a taxonomy. Its lesson: the same system looks genuinely different from different cells, and confusing the cells causes much avoidable conflict.