The four dimensions used to scope an architecture are Breadth, Depth, Time Period, and Architecture Domains. Breadth refers to the extent of the enterprise covered by the architecture. Depth refers to the level of detail and completeness of the architecture. Time Period refers to the planning horizon and the number of Transition Architectures required to achieve the Target Architecture. Architecture Domains refer to the four domains of Business, Data, Application, and Technology that constitute an enterprise's architecture. Reference: The TOGAF Standard | The Open Group Website, Section 3.2.1 Phase A: Architecture Vision.