ASTRO Site Repeater, aka a standalone trunked site. I've always felt that it should've really been termed ASTRO Repeater Site, as ASR sounds like it's a single repeater at a site. 🤷♂️
Edit: "standalone" simply meaning not part of a simulcast cell, but rather a single RF site. It can and usually is connected to the rest of the system, carrying whatever traffic it needs to carry, so it's not "standalone" in that sense. Back in the 4.1 days they were referred to as IntelliRepeater sites (IR), however the modern ASR is a fully capable site and is otherwise indistinguishable from an simulcast cell as far as functionality and features.