Adding a few PHPDoc blocks.

library/App/Model/ApprovalActionInterface.php

 <?php
 
+/**
+ * Provides an interface for creating additional Approval Action types.
+ * An approval action represents a point at which some entity may potentially
+ * modify a request and then make a decision about the request (by modifying
+ * its status).  A Model implementing this interface will be a child of Unl_Model.
+ */
+
 interface App_Model_ApprovalActionInterface
 {
 	/**

library/App/RequestNotification.php

 <?php
 
+/**
+ * This class handles the generation and scheduling of email notifications
+ * that alert users of requests that are pending their decisions.
+ */
+
 class App_RequestNotification
 {
+	/**
+	 * Stores the list of notifications once it has been generated to avoid
+	 * needlessly reproccessing it.
+	 * 
+	 * @var array
+	 */
 	static protected $_notifications;
 	
+	/**
+	 * Does the work of processing which users have pending requests and populates
+	 * $_notifications with the list.
+	 */
     static protected function _loadNotifications()
     {
     	if (Unl_Util::isArray(self::$_notifications)) {
@@ -81,6 +96,10 @@ class App_RequestNotification
         }
     }
     
+    /**
+     * Prints out a simple list of the notifications in plain text.
+     * Mainly useful when debugging.
+     */
     public static function listNotifications()
     {
     	self::_loadNotifications();
@@ -93,6 +112,9 @@ class App_RequestNotification
     	}
     }
     
+    /**
+     * Sends out an email to each user who has pending requests.
+     */
     public static function sendNotifications()
     {
         self::_loadNotifications();
@@ -150,6 +172,10 @@ EOF
         }
     }
     
+    /**
+     * Sends out email notifications, then schedules itself to be called again in two days.
+     * This should really only be called by a cron job.
+     */
     public static function scheduledNotifications()
     {
     	self::sendNotifications();