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Plate TPL·011 · TemplateGrid H3 · Rev. 2026-09-14

Product Specification

A feature specification that covers states, edge cases and accessibility rather than only the happy path.

TemplateCraft conventionIntermediate

Definition

A specification defines what will be built precisely enough to implement and to test. Most specifications fail by describing only the successful case.

Craft convention. True because the industry converged on it. Breaking it costs familiarity, not correctness.

On this plate
  1. 1Definition
  2. 2The cases specifications usually omit
  3. 3Specifying
  4. 4Local chart
  5. 5Continue from here

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Definition

One paragraph. If it takes more, the scope is probably too large.

What the user achieves, and how you would verify it in a test.

Explicit boundaries prevent scope drift during build.

Behaviour

Steps, with the system's response at each.

Empty, loading, partial, error, success, offline, permission denied.

Zero, one, many, maximum, longest content, slowest response, permission variations.

Requirements

Keyboard, focus, labels, announcements, contrast, motion.

Every string the interface needs, written out, not described.

Anything requiring a decision before build. Assign each one.

The cases specifications usually omit

Each row is a question that gets answered either in the specification or by whoever is implementing it at the time, alone.

CaseQuestion to answerWhat ships without it
Nothing there yetWhat does this show before any data exists?A blank region that reads as a failure.
Too much, or too longMaximum counts, longest string, what truncates and what wrapsA layout that breaks on the first real customer name.
Not permittedHidden, disabled with a reason, or visible and refused?A control that fails silently for half the users.
Slow or offlineWhat is shown, what is queued, what is lostA spinner with no end state.
Two people at onceWho wins, and what the loser is toldSilent overwrite, discovered later.
Time and placeWhose timezone, which locale, how dates and currency are formattedA daily total that is wrong for anyone outside head office.
Accessibility contractRole, name, keyboard behaviour, announced stateA feature that has to be rebuilt to be used at all.

Specifying

Do

  • Write each requirement so it can be verified, since an unverifiable requirement is a preference.
  • Say what is deliberately not included, and why, so it is not re-litigated in review.
  • Specify the behaviour, and leave the implementation to the people implementing it.
  • Include the states and the accessibility contract in the same document, not in a separate pass that never happens.

Do not

  • Do not describe only the successful path.
  • Do not use words that cannot be tested: fast, intuitive, seamless, clean.
  • Do not bury a decision in a comment thread. If it governs the build, it belongs in the specification.
  • Do not let the specification and the built product drift apart silently. Update it, or mark it superseded.

Local chart

TPL·011 · Region VIII · Grid H3

This entry and the entries it is stated to connect with. Each line is labelled with what the connection means.

Feature Idea to UX SpecificationAI·004 · OFTEN USED WITHPRD to User FlowAI·002 · OFTEN USED WITHJobs to Be DoneRES·018 · OFTEN USED WITHDesign BriefTPL·010 · OFTEN USED WITHStory MapTPL·006 · OFTEN USED WITHUser FlowTPL·005 · OFTEN USED WITHAxure RPTOOL·012 · OFTEN USED WITHConfluenceTOOL·045 · OFTEN USED WITHNotionTOOL·044 · OFTEN USED WITHZeplinTOOL·043 · OFTEN USED WITHVisual StatesFND·053 · OFTEN USED WITHDesign HandoffFLOW·002 · OFTEN USED WITH

Continue from here

Each link says what the connection is, so you can tell a principle from an alternative from a thing people mix this up with.

Applies when you are designing

A DashboardA Data TableA FormAn AI ProductAn Enterprise WorkflowAuthenticationSettings

Often used with

These usually appear in the same screen or the same decision.

Short definition

The one-paragraph version, for when that is all you need.