Phase C develops the Information Systems Architectures — the Data and Application architectures together. It's where the business intent from Phase B becomes the systems that will carry it. Getting the sequencing right (data vs application first) is a favourite exam point.

Phase C develops the Target Data and Application Architectures and analyses gaps vs the baseline. Data and Application are done together because they're tightly coupled, but you may develop Data first then Application, or Application first then Data, depending on the situation — TOGAF allows either sequence.

Data Architecture — the major data types and sources needed to support the business, independent of specific applications (avoid getting drawn into database design). Key artifacts: data entity catalogs, the Data Entity/Business Function matrix, data dissemination diagrams.

Application Architecture — the applications needed to process the data and support the business, described as logical groups of capability (not a system design). Key artifacts: application portfolio catalog, application/function matrix, application communication diagrams.

Phase C is bounded by Phase B (business) and constrains Phase D (technology that hosts the applications and data). Its gaps join the others and flow to Phase E. The Data and Application domains are two of the four BDAT domains (TGF‑C1).