Calender with a roll stack and process for arranging rolls in a roll stack of a calender, the calender comprising two end rolls in a press plane and a plurality of middle rolls between the two end rolls. Each link includes a unique password embedded therein and each unique password relates to a particular user identification and personal identification number. In the system a query-free information retrieval system is described in which the exact technical documentation contained in existing user or other technical manuals is provided to a user investigating apparatus having a fault.