IMPORTANT NOTE: Think twice before restricting read or write access to a web or a topic, because an open system where everybody can contribute is the essence of the WikiCulture. Experience shows that unrestricted write access works very well because:

• A topic revision can be undone by a member of the TWikiAdminGroup in case needed.

• ALLOWTOPICCHANGE defines who is allowed to change the group topic; it is a comma delimited list of users and groups. You typically want to restrict that to the members of the group itself, so it should contain the name of the topic, i.e.
      * Set ALLOWTOPICCHANGE = Public.TWikiAdminGroup
  for the TWikiAdminGroup topic. (This is to prevent users not in the group from editing the topic and gaining unauthorized membership to the group.)

• DENYTOPICCHANGE (in topic) overrides DENYWEBCHANGE (in WebPreferences)
• ALLOWTOPICCHANGE (in topic) overrides ALLOWWEBCHANGE (in WebPreferences)