diff --git a/archive.js b/archive.js
index 0527d83..a6c4b75 100644
--- a/archive.js
+++ b/archive.js
@@ -13,22 +13,61 @@ bitjs.archive = bitjs.archive || {};
 
 (function() {
 
-bitjs.archive.UnarchiveEvent = funciton() {
-  this.type  
+/**
+ * @param {string} type The event type.
+ * @constructor
+ */
+bitjs.archive.UnarchiveEvent = function(type) {
+  this.type = type;
 };
 
-bitjs.archive.Unarchiver = function() {
-  this.listeners_ = [];
+bitjs.archive.UnarchiveEvent.Type = {
+  START: 'bitjs.archive.UnarchiveEvent.START',
+  PROGRESS: 'bitjs.archive.UnarchiveEvent.PROGRESS',
+  EXTRACTION: 'bitjs.archive.UnarchiveEvent.EXTRACTION',
+  FINISH: 'bitjs.archive.UnarchiveEvent.FINISH',
+  ERROR: 'bitjs.archive.UnarchiveEvent.ERROR'
 };
 
+/**
+ * Base abstract class for all Unarchivers.
+ *
+ * @param {ArrayBuffer} arrayBuffer The Array Buffer.
+ */
+bitjs.archive.Unarchiver = function(arrayBuffer) {
+  /**
+   * @type {ArrayBuffer}
+   */
+  this.ab_ = arrayBuffer;
+
+  /**
+   * A map from event type to an array of listeners.
+   * @type {Map.<string, Array>}
+   */
+  this.listeners_ = {
+    bitjs.archive.UnarchiveEvent.Type.START: [],
+    bitjs.archive.UnarchiveEvent.Type.PROGRESS: [],
+    bitjs.archive.UnarchiveEvent.Type.EXTRACTION: [],
+    bitjs.archive.UnarchiveEvent.Type.FINISH: [],
+    bitjs.archive.UnarchiveEvent.Type.ERROR: []
+  };
+};
+
+/**
+ *
+ */
 bitjs.archive.Unarchiver.prototype.addEventListener = function() {
-  
 };
 
+/**
+ *
+ */
 bitjs.archive.Unarchiver.prototype.removeEventListener = function() {
-  
 };
 
+/**
+ * Abstract method - do not call directly.
+ */
 bitjs.archive.Unarchiver.prototype.unarchive = function() {
   throw "Error!  Abstract method unarchive() in bitjs.archive.Unarchiver called";
 };