special commands were also available. for example, to facilitate movement around the database it was possible to step back through a maximum of 3 frames or pages by use of the special key combination "*#". in the event of corruption of a page in transmission it was possible to refresh the page by means of the code *00, which had the advantage of avoiding any page charge being raised again. alternatively, if the user wished to update a page to see the latest information, for example of flight arrival times, the *09 command would retrieve the latest updates, at the same time re-billing any page display charge. if all else failed, a user could simply return to the first page which he saw after logging onto the system by use of the *0# combination, which brought up their default main index. exceptionally, information could be hidden on a frame by an ip which could only be revealed by use of the 'reveal" key of the keypad (e.g., to show an answer to a quiz). the same 'reveal' key was also used to hide the data once more.