Concepts often contain the most fundamental solution approaches. Understanding these concepts is prerequisite for understanding the architecture.

Concepts form the basis for conceptual integrity (consistency, homogeneity) of the architecture.

They provide stereotypical solutions to recurring problems.

You can often save a lot of documentation effort by explaining concepts, instead of concentrating on building block details.

Crosscutting means exactly what it says: a concept is not the property of any single building block, but a decision that several of them share. That is why it does not belong in any one building block description - it would have to be repeated in each of them.

A concept does not have to run through every building block to be crosscutting - spanning several of them is enough.

Find a few potential topics for such crosscutting concepts in the following diagram: