diff --git a/README.md b/README.md
index 01c18e2..1987e3b 100644
--- a/README.md
+++ b/README.md
@@ -26,15 +26,15 @@ API documentation is available [here](https://bitchan.github.io/bitmessage/docs/
   - [ ] AES-256-CBC
   - [ ] HMAC-SHA-256
 - [ ] Common structures
-  - [ ] message
+  - [x] message
   - [x] var_int
   - [x] var_str
   - [x] var_int_list
   - [ ] net_addr
-  - [ ] inv_vect
   - [ ] encrypted
-  - [ ] encoding
-  - [ ] bitfield
+  - [x] message encodings
+  - [ ] service features
+  - [ ] pubkey features
 - [ ] Message types
   - [ ] version
   - [ ] verack
diff --git a/lib/structs.js b/lib/structs.js
index 364b47c..07f5c30 100644
--- a/lib/structs.js
+++ b/lib/structs.js
@@ -6,6 +6,7 @@
 
 "use strict";
 
+require("object.assign").shim();
 var assert = require("assert");
 var bufferEqual = require("buffer-equal");
 var bmcrypto = require("./crypto");
@@ -249,3 +250,19 @@ exports.var_int_list = {
     return Buffer.concat([var_int.encode(list.length), listBuf]);
   },
 };
+
+exports.messageEncodings = Object.create(var_int);
+Object.assign(exports.messageEncodings, {
+  IGNORE: 0,
+  TRIVIAL: 1,
+  SIMPLE: 2,
+});
+
+exports.serviceFeatures = {
+  NODE_NETWORK: 1,
+};
+
+exports.pubkeyFeatures = {
+  INCLUDE_DESTINATION: 30,
+  DOES_ACK: 31,
+};