diff --git a/README b/README
index 418a88b1f236ae5082edea6b8fb88462f3777b7e..49db7cdd7a1ec649490ab432e37a7346413be0b1 100644
--- a/README
+++ b/README
@@ -46,7 +46,7 @@ Extensions and their implementation status:
   Base specification (RFC3028):
     fileinto: validation and generation
     reject: validation and generation
-    envelope: validation and generation
+    envelope: full
 	encoded-character: planned (draft-ietf-sieve-3028bis)
 
   Other RFCs/drafts:
@@ -94,6 +94,8 @@ INTERPRETER: sieve-interpreter.c
 TODO
 ----
 
+* Resolve code duplication introduced for handling address-parts and match-types
+  in different command implementations. 
 * Further implement error handling and limit the maximum number of errors. 
 * Resolve code duplication amongst comparator, address-part and match-type 
   support as much as possible. 
diff --git a/src/lib-sieve/ext-envelope.c b/src/lib-sieve/ext-envelope.c
index c7ef709f0471499623bd520bcf3bf5c6b1da84f7..d46104951863078be81e22161ee4e868a50a5e34 100644
--- a/src/lib-sieve/ext-envelope.c
+++ b/src/lib-sieve/ext-envelope.c
@@ -1,3 +1,13 @@
+/* Extension envelope 
+ * ------------------
+ *
+ * Authors: Stephan Bosch
+ * Specification: RFC3028
+ * Implementation: full
+ * Status: experimental, largely untested
+ *
+ */
+
 #include <stdio.h>
 
 #include "lib.h"