Phase B develops the Business Architecture — the first of the three domain phases. It matters because Data, Application and Technology only make sense in service of the business: you can't sensibly design systems (C) or infrastructure (D) until the business processes, capabilities and organisation are understood.

It's also where the ADM's gap analysis rhythm first appears in earnest.

Phase B develops the Target Business Architecture describing how the enterprise needs to operate to achieve the business goals and the Architecture Vision, and it analyses the gaps between the Baseline and Target. It selects relevant viewpoints (e.g. organisation, functions, processes) and the tools/techniques to use.

Steps: develop the Baseline Business Architecture, develop the Target, perform gap analysis (what must be added/removed/changed), define candidate roadmap components, and resolve impacts across the landscape. The gap output feeds Phase E.

Typical artifacts: business capability maps, value streams, organisation/functional decomposition, process flows.

Phase B is bounded by the Vision (A) and the principles/governance (Preliminary). Its outputs constrain Phase C (the Information Systems that support the business) and its gaps flow to Phase E. Requirements surface and update through Requirements Management at the centre.