Tags (see https://git.iws.uni-stuttgart.de/dumux-repositories/dumux/-/blob/master/dumux/common/tag.hh) have some advantages over enums and, as far as I know, no disadvantages (edit: one disadvantage is that interfaces receiving a method as an argument need to be templated while this is not necessary for the enum implementation). The most prominent advantage being that a new tag can be added in user code without modifying the `discretization/method.hh` header which is currently required. This makes is difficult/impossible to add a new discretization in a separate module. Tags have been introduced for the `CouplingMode` in [couplingmanager1d3d.hh](https://git.iws.uni-stuttgart.de/dumux-repositories/dumux/-/blob/master/dumux/multidomain/embedded/couplingmanager1d3d.hh) which previously was an enum and enabled implemented new modes in downstream modules. There was also a deprecation period possible which should be possible for the discretization method as well. !2795 !2844