web- the web which was being accessed
topic- the topic being accessed (if any)
user- canonical username of the person doing the accessing. Use the methods of the TWiki::Users class to get more information about the user.
mode- the access mode e.g. CHANGE, VIEW etc
reasona text string giving the reason for the refusal.
$mode- mode of access (view, change etc)
$user- canonical user name of user doing the accessing
$web- web being accessed
$topic- topic being accessed
$reason- string reason for failure