Semi-Rimmed
A case design with a small rim that protrudes slightly past the body, both setting headspace and aiding extraction, between rimmed and rimless.
A semi-rimmed case has a rim that is only a little wider than the body, leaving a shallow extractor groove cut just ahead of it. That slight overhang at the case head gives the extractor something to grab and usually sets headspace on the rim, much like a rimmed case but far less pronounced. The .220 Swift and .38 Super are well-known examples of the layout.
This design splits the difference between a fully rimmed case and a flush rimless one. The small rim still helps in some extraction and feeding situations, while the minimal overhang stacks more cleanly in a box magazine than a tall rim would. For modern precision rifles the rimless head dominates, but the semi-rimmed form survives in a handful of older and specialized cartridges.