Note that scattering and tangling describe the representation of a concern within an artifact. So a given concern (i.e. a use case) might not be scattered within one representation of a system such as documentation, but might be scattered and tangled within another representation source code.
It is important to note that many separation of concern mechanisms can be used to solve scattering and tangling. Which mechanism to use depends on a number of particulars, including the structure of the artifacts and the structure of the concern. So for example, procedures are often a useful mechanism to solve scattering and tangling. As are classes. AOSD techniques are useful when the scattering arises from an underlying crosscutting structure among the concerns.