# System.Diagnostics.CodeAnalysis

``` diff
 namespace System.Diagnostics.CodeAnalysis {
+    [AttributeUsageAttribute(AttributeTargets.Assembly | AttributeTargets.Class | AttributeTargets.Constructor | AttributeTargets.Delegate | AttributeTargets.Enum | AttributeTargets.Event | AttributeTargets.Field | AttributeTargets.Interface | AttributeTargets.Method | AttributeTargets.Module | AttributeTargets.Property | AttributeTargets.Struct, Inherited=false)]
+    public sealed class ExperimentalAttribute : Attribute {
+        public ExperimentalAttribute(string diagnosticId);
+        public string DiagnosticId { get; }
+        public string? UrlFormat { get; set; }
+    }
 }
```

