Huge +1. I've mentioned this in a couple PRs and JIRAs but the Unicode.Scalar.Properties APIs are difficult to trust on Linux without a known version of ICU being built into the standard library. On Apple platforms we can at least make specific properties @available based on OS releases that map to ICU versions, but we don't have that ability for Linux, so there's no way (without something extreme, like checking the ICU version at runtime) to distinguish between "this property is false" vs. "this property isn't supported" in client code.