diff --git a/lib/bindings/http/constants.js b/lib/bindings/http/constants.js
index 803b077..afb541e 100644
--- a/lib/bindings/http/constants.js
+++ b/lib/bindings/http/constants.js
@@ -3,6 +3,11 @@ module.exports = {
   HEADERS : "headers",
   CHARSET_DEFAULT : "utf-8",
 
+  SPEC_V02 : "0.2",
+  SPEC_V03 : "0.3",
+
+  DEFAULT_SPEC_VERSION_HEADER : "ce-specversion",
+
   DATA_ATTRIBUTE : "data",
 
   MIME_JSON         : "application/json",