diff --git a/classes/shibd_discofeed.class.php b/classes/shibd_discofeed.class.php
index 990c06b4abb5185deb35a641227c8639ad39f98c..8e78d0836f2bf8278c96524f23383edf7b72e10d 100644
--- a/classes/shibd_discofeed.class.php
+++ b/classes/shibd_discofeed.class.php
@@ -7,6 +7,16 @@
  * included functions
  * License: GNU GPL 3.0
  * Source: https://git-repo.iml.unibe.ch/iml-open-source/login-aai
+ * 
+ * ----------------------------------------------------------------------
+ * 
+ * Shibboleth discofeed
+ * 
+ * Reads the Shibboleth discofeed and returns a list of idps.
+ * This list will be cached in a json file.
+ * With the list of idps, you get a subset by filtering with a
+ * positive list of entity ids.
+ * 
  * ======================================================================
  */
 class shibd_discofeed
@@ -48,7 +58,12 @@ class shibd_discofeed
      * @var string
      */
     protected string $SELFURL = '';
-    // protected array $aConfig = [];
+
+    /**
+     * Configuration array for current web app
+     * @var array
+     */
+    protected array $aConfig = [];
 
     // ----------------------------------------------------------------------
 
@@ -88,6 +103,7 @@ class shibd_discofeed
     /**
      * Get List if IDPs from cache file if possible 
      * or from Shibboleth Disco feed and write a cache file
+     * 
      * @return array
      */
     function getAllIdps(): array
@@ -109,7 +125,17 @@ class shibd_discofeed
     }
 
     /**
-     * Get list of active IDPs
+     * Get list of active IDPs.
+     * The entries per item from discofeed will be extended with some more 
+     * subkeys:
+     *    '_label'       Language specific label from 'DisplayNames'
+     *    '_description  Language specific description from 'Descriptions'
+     *    '_keywords     Language specific keywords from 'Keywords'
+     *    '_image'       Image from 'Logos' item 1
+     *    '_url'         Generates static login url for this IDP
+     *    '_idpdomain    Hostname of the IDP
+     *    '_tld'         TLD of the IDP, eg '.ch', '.de'
+     * 
      * @return array
      */
     public function getIdps(): array