diff --git a/README.md b/README.md
index 94bc4e7..75386d0 100644
--- a/README.md
+++ b/README.md
@@ -50,6 +50,7 @@ With the help of browserify `bitmessage` provides different implementations for
   - [ ] addr
   - [ ] inv
   - [ ] getdata
+  - [ ] error
   - [ ] object
 - [ ] Object types
   - [ ] getpubkey
diff --git a/lib/index.js b/lib/index.js
index 383b89b..f6de2fb 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -7,7 +7,15 @@
 
 /** Common structures. */
 exports.struct = require("./struct");
+/** Messages. */
+exports.message = require("./message");
+/** Objects. */
+exports.object = require("./object");
+
 /** Working with WIF. */
 exports.WIF = require("./wif");
+/** Proof of work. */
+exports.POW = require("./pow");
+
 /** Working with addresses. */
 exports.Address = require("./address");
diff --git a/lib/message.js b/lib/message.js
new file mode 100644
index 0000000..aa42f6d
--- /dev/null
+++ b/lib/message.js
@@ -0,0 +1,5 @@
+/**
+ * Working with messages.
+ * @see {@link https://bitmessage.org/wiki/Protocol_specification#Message_types}
+ * @module bitmessage/message
+ */
diff --git a/lib/object.js b/lib/object.js
new file mode 100644
index 0000000..9a8b78e
--- /dev/null
+++ b/lib/object.js
@@ -0,0 +1,5 @@
+/**
+ * Working with objects.
+ * @see {@link https://bitmessage.org/wiki/Protocol_specification#Object_types}
+ * @module bitmessage/object
+ */
diff --git a/lib/pow.js b/lib/pow.js
new file mode 100644
index 0000000..795bfba
--- /dev/null
+++ b/lib/pow.js
@@ -0,0 +1,5 @@
+/**
+ * Implements proof of work.
+ * @see {@link https://bitmessage.org/wiki/Proof_of_work}
+ * @module bitmessage/pow
+ */