Build a decision requirements diagram

The requirements diagram says which decisions exist, what data they need, and what governs them. Drawing it first stops you writing one enormous table that should have been three.

The authority links are the part auditors ask about: which policy or regulation a rule comes from.


#What this is for

  • Any decision built from more than one sub-decision.

  • Governance work, where the source of a rule matters.

  • Planning before writing any table logic.


#How it works

Action

How

Decision

A rectangle. Produces an output from its inputs.

Input data

Rounded ends. Data supplied from outside the model.

Business knowledge model

Clipped corners. Reusable logic several decisions share.

Knowledge source

Wavy bottom. The authority: a policy, a regulation, a person.

Information requirement

Solid arrow, into a decision.

Authority requirement

Dashed arrow, from a knowledge source.


#A few things that catch people out

  • Solid and dashed arrows mean different things. Information flows; authority governs.

  • A decision with five information requirements is usually two decisions.

  • Name knowledge sources specifically. "Policy" helps nobody; "Credit policy 2026 v3" does.



Draw the map before writing the rules.