diff --git a/enrol/authorize/const.php b/enrol/authorize/const.php
index 9079c7cc31c..2384fc8a3dc 100644
--- a/enrol/authorize/const.php
+++ b/enrol/authorize/const.php
@@ -1,88 +1,57 @@
 <?php // $Id$
 
-/**
- * New order. No transaction was made.
- */
-define('AN_STATUS_NONE',    0x00);
-
-/**
- * Authorized.
- */
-define('AN_STATUS_AUTH',    0x01);
-
-/**
- * Captured.
- */
-define('AN_STATUS_CAPTURE', 0x02);
-
-/**
- * AN_STATUS_AUTH|AN_STATUS_CAPTURE.
+/**#@+
+ * Order status used in enrol_authorize table.
+ *
+ * NONE: New order or order is in progress. TransactionID hasn't received yet.
+ * AUTH: Authorized/Pending Capture.
+ * CAPTURE: Captured.
+ * AUTHCAPTURE: Authorized/Captured
+ * CREDIT: Refunded.
+ * VOID: Cancelled.
+ * EXPIRE: Expired. Orders be expired unless be accepted within 30 days.
+ * TEST: Tested. It means created in TEST mode and TransactionID is 0.
  */
+define('AN_STATUS_NONE',        0x00);
+define('AN_STATUS_AUTH',        0x01);
+define('AN_STATUS_CAPTURE',     0x02);
 define('AN_STATUS_AUTHCAPTURE', 0x03);
+define('AN_STATUS_CREDIT',      0x04);
+define('AN_STATUS_VOID',        0x08);
+define('AN_STATUS_EXPIRE',      0x10);
+define('AN_STATUS_TEST',        0x80);
+/**#@-*/
 
-/**
- * Refunded.
- */
-define('AN_STATUS_CREDIT', 0x04);
-
-/**
- * Voided.
- */
-define('AN_STATUS_VOID', 0x08);
-
-/**
- * Expired.
- */
-define('AN_STATUS_EXPIRE', 0x10);
-
-/**
- * Tested.
- */
-define('AN_STATUS_TEST', 0x80);
-
-/**
- * No action.
- */
-define('AN_ACTION_NONE', 0x00);
-
-/**
- * Used to authorize only, don't capture.
- */
-define('AN_ACTION_AUTH_ONLY', 0x01);
-
-/**
- * Used to capture, it was authorized before.
- */
-define('AN_ACTION_PRIOR_AUTH_CAPTURE', 0x02);
-
-/**
- * Used to authorize and capture.
- */
-define('AN_ACTION_AUTH_CAPTURE', 0x03);
-
-/**
- * Used to return funds to a customer's credit card.
+/**#@+
+ * Actions used in authorizenet_action function.
  *
- * - Can be credited within 120 days after the original authorization was obtained.
- * - Amount can be any amount up to the original amount charged.
- * - Captured/pending settlement transactions cannot be credited,
- *   instead a void must be issued to cancel the settlement.
- * NOTE: Assigns a new transactionID to the original transaction.
- *       SAVE IT, so we can cancel new refund if it is a fault return.
- */
-define('AN_ACTION_CREDIT', 0x04);
-
-/**
- * Used to cancel an exiting transaction with a status of
- * authorized/pending capture, captured/pending settlement or
- * settled/refunded.
+ * NONE: No action. Function always returns false.
+ * AUTH_ONLY: Used to authorize only, don't capture.
+ * PRIOR_AUTH_CAPTURE:  Used to capture, it was authorized before.
+ * AUTH_CAPTURE: Used to authorize and capture.
+ * CREDIT: Used to return funds to a customer's credit card.
+ * VOID: Used to cancel an exiting pending transaction.
  *
- * - Void requests effectively cancel the Capture request
- *   that would start the funds transfer process.
- * - Also used to cancel existing transaction with a status of
- *   settled/refunded. Credited mistakenly, so cancel it
- *   and return funds to our account.
+ * Credit rules:
+ *  1. It can be credited within 120 days after the original authorization was obtained.
+ *  2. Amount can be any amount up to the original amount charged.
+ *  3. Captured/pending settlement transactions cannot be credited,
+ *     instead a void must be issued to cancel the settlement.
+ *  NOTE: It assigns a new transactionID to the original transaction.
+ *        We should save it, so admin can cancel new transaction if it is a mistake return.
+ *
+ * Void rules:
+ *  1. These requests effectively cancel the Capture request that would start the funds transfer process.
+ *  2. It mustn't be settled. Please set up settlement date correctly.
+ *  3. These transactions can be voided:
+ *     authorized/pending capture, captured/pending settlement, credited/pending settlement
  */
-define('AN_ACTION_VOID', 0x08);
+define('AN_ACTION_NONE',                0x00);
+define('AN_ACTION_AUTH_ONLY',           0x01);
+define('AN_ACTION_PRIOR_AUTH_CAPTURE',  0x02);
+define('AN_ACTION_AUTH_CAPTURE',        0x03);
+define('AN_ACTION_CREDIT',              0x04);
+define('AN_ACTION_VOID',                0x08);
+/**#@-*/
 
 ?>