@@ -5,5 +5,8 @@
         public const string UnkownService = "UnkownService";
         public const string UnkownApp = "UnkownApp";
         public const string WebAppType = "web";
+        // TODO:bertrand expose these publicly?
+        public const string HttpHeaderTraceId = "x-datadog-trace-id";
+        public const string HttpHeaderParentId = "x-datadog-parent-id";
     }
 }
﻿namespace Datadog.Trace
{
    internal static class Constants
    {
        public const string UnkownService = "UnkownService";
        public const string UnkownApp = "UnkownApp";
        public const string WebAppType = "web";
    }
}

I think no. To me the public API of our tracer is the `Tracer` class that creates spans and contexts. This means that if you want to inject/extract, you should always pass by our `Tracer#inject` or `Tracer#extract`. The surface of the API must be minimal so I think there is no need to expose such headers to users.