capability-map

Start from business outcomes rather than the org chart, then decompose top-down into L1 areas, L2 sub-functions, and L3 capabilities. Stop decomposing when a capability maps to a single accountable owner, typically yielding 8 to 12 L1 capabilities.

A capability describes what the business does, not how it does it. Capabilities remain stable for decades while applications and processes change frequently, which makes them a durable basis for architecture decisions.

Classify each L3 capability by differentiation: Core capabilities differentiate the business and should be built internally, Supporting ones are necessary but can be bought or configured, and Commodity ones can be outsourced or handled by SaaS.

Overlay each L3 capability with the applications that deliver it. Two systems serving the same capability signal duplication, a capability with no system signals a gap, and one system spanning many L1 areas signals a monolith.

Stop when a capability corresponds to exactly one accountable owner. The quality criteria require every L3 capability to have a single owner, a classification, and a system overlay before the map is considered complete.