BRD vs SRD: business requirements vs system requirements

A BRD (Business Requirements Document) captures why the business is doing this at all — the goals, the scope, the success measures, the constraints from the business side. An SRD (Software/System Requirements Document) captures how the system must behave to satisfy those goals — concrete, testable requirements for engineering.

They're the bookends of a requirements chain. The BRD is furthest from code; the SRD is closest to it.

	BRD	SRD
Answers	Why the business wants it	How the system must behave
Audience	Leadership, sponsors, stakeholders	Engineers, QA
Contains	Business goals, scope, success metrics, constraints	Functional & non-functional requirements, acceptance criteria
Altitude	Business-level	Behavior-level
Time horizon	Strategic	Build-ready

The missing middle

Jump straight from a BRD to an SRD and you'll feel the gap: the business said “we want to reduce churn,” and now engineering needs exact behaviors. Something has to translate business goals into a product solution first. That something is the PRD.

So the real chain is BRD → PRD → SRD: business need, product solution, system spec. Skip the middle and engineers end up inventing product decisions that were never theirs to make.

Grounding the chain

Cadenly covers the chain end to end: the business-level thinking (goals, scope) in Scope Refinement and the Living Plan, the product solution in the PRD workflow, and the system-level spec — stories, sizing, architecture — in the Spec workflow. Because each stage is grounded in the same product memory, the SRD traces back to the business goal it serves instead of drifting.