NotImplementedException annotation.

src/System.Private.CoreLib/src/System/IO/Stream.cs

@@ -660,7 +660,7 @@ public override int ReadByte()
 
             public override IAsyncResult BeginRead(byte[] buffer, int offset, int count, AsyncCallback callback, Object state)
             {
-                throw new NotImplementedException();
+                throw new NotImplementedException(); // TODO: https://github.com/dotnet/corert/issues/3251
                 //bool overridesBeginRead = _stream.HasOverriddenBeginEndRead();
 
                 //lock (_stream)
@@ -712,7 +712,7 @@ public override void WriteByte(byte b)
 
             public override IAsyncResult BeginWrite(byte[] buffer, int offset, int count, AsyncCallback callback, Object state)
             {
-                throw new NotImplementedException();
+                throw new NotImplementedException(); // TODO: https://github.com/dotnet/corert/issues/3251
                 //bool overridesBeginWrite = _stream.HasOverriddenBeginEndWrite();
 
                 //lock (_stream)

src/System.Private.CoreLib/src/System/Reflection/Assembly.CoreRT.cs

@@ -14,7 +14,7 @@ public abstract partial class Assembly : ICustomAttributeProvider, ISerializable
         public static Assembly GetEntryAssembly() => Internal.Runtime.CompilerHelpers.StartupCodeHelpers.GetEntryAssembly();
 
         [System.Runtime.CompilerServices.Intrinsic]
-        public static Assembly GetExecutingAssembly() { throw new NotImplementedException(); }
+        public static Assembly GetExecutingAssembly() { throw NotImplemented.ByDesign; } //Implemented by toolchain. 
 
         public static Assembly GetCallingAssembly() { throw new PlatformNotSupportedException(); }
 

src/System.Private.CoreLib/src/System/Reflection/AssemblyName.cs

@@ -224,8 +224,8 @@ public void OnDeserialization(object sender)
             _siInfo = null;
         }
 
-        public static AssemblyName GetAssemblyName(string assemblyFile) { throw new NotImplementedException(); }
-        public static bool ReferenceMatchesDefinition(AssemblyName reference, AssemblyName definition) { throw new NotImplementedException(); }
+        public static AssemblyName GetAssemblyName(string assemblyFile) { throw new NotImplementedException(); } // TODO: https://github.com/dotnet/corert/issues/3253
+        public static bool ReferenceMatchesDefinition(AssemblyName reference, AssemblyName definition) { throw new NotImplementedException(); } // TODO: https://github.com/dotnet/corert/issues/1861
 
         internal static string EscapeCodeBase(string codebase) { throw new PlatformNotSupportedException(); }
 

src/System.Private.CoreLib/src/System/Reflection/MethodBase.CoreRT.cs

@@ -12,7 +12,7 @@ public abstract partial class MethodBase : MemberInfo
         public static MethodBase GetMethodFromHandle(RuntimeMethodHandle handle, RuntimeTypeHandle declaringType) => ReflectionAugments.ReflectionCoreCallbacks.GetMethodFromHandle(handle, declaringType);
 
         [System.Runtime.CompilerServices.Intrinsic]
-        public static MethodBase GetCurrentMethod() { throw new NotImplementedException(); }
+        public static MethodBase GetCurrentMethod() { throw NotImplemented.ByDesign; } //Implemented by toolchain.
 
         // This is not an api but needs to be declared public so that System.Private.Reflection.Core can access (and override it)
         public virtual ParameterInfo[] GetParametersNoCopy() => GetParameters();