[[P3045R7]](https://wg21.link/p3045r7) proposes a C++ quantities and units framework built on two core abstractions: `quantity` (displacement vectors) and `quantity_point` (points in an affine space). Real-world experience with the **[[mp-units]](https://mpusz.github.io/mp-units)** reference implementation, together with feedback from SG6, BSI, ANSI, and the broader C++ community, shows that this two-abstraction model is insufficient for several common engineering patterns and, in places, mathematically too permissive.