A Building Block defines a single infrastructure function.
Each Working Area has its own Building Block Types, of which there may exist one or more Building Block Variants. The Building Block Type defines what the Building Block does, the Building Block Variant describes how the Building Block must fit into a specific Environment.
The definition of a Building Block Type on an architectural level consists of a functional description that contains
- the purpose,
- the service offered, and
- the manner in which the Building Block is used and maintained.
The definition of a Building Block Variant may point back to the definition of the Building Block Type from which it is derived, so that all functional descriptions can be omitted from the Variant description. What then constitutes a Building Block Variant is:
- the Environment (or multiple Environments) in which this Variant operates,
- optional remarks and requirements that concern the design, implementation, operation and end-of-life of this specific Variant of the Building Block,
- the set of Quality Requirements that are demanded by that Environment, and
- the (set of) Elements that the architects want to prescribe to the designers.