This filter reduces the amount of documents, which are delegated by a group to users. The users receive only documents that meet with the filter conditions. The filters can be controlled for example in Monitoring - > Reports as administrator. The filter describes which documents are delegated to the user. For example w03_u04_ai_dst=5 means that this user gets all documents for the user-ID 5. According to this the user has the ID 5. Is the user additionally in the group with the ID 21, the filter is (w03_u04_ai_dst=5 or (w03_u04_ai_dst=21)). Administrators can add a filter to a group while he edits this group.  Group members only get documents if these documents meet the filter conditions.