# System.Runtime.CompilerServices

``` diff
 namespace System.Runtime.CompilerServices {
+    [AttributeUsageAttribute(AttributeTargets.Module, AllowMultiple=false, Inherited=false)]
+    public sealed class RefSafetyRulesAttribute : Attribute {
+        public RefSafetyRulesAttribute(int version);
+        public int Version { get; }
+    }
 }
```

