Hi,
According to the described situation, you close all to all (* @ALL 0) then open to users or better choice to groups putting ACL on pages or namespaces. You have good explanations and examples in the
ACL doc that would help you. A wiki organised by
namespaces for groups is easier, users can belong to multiple groups. Who(groups) can do What(ACL) Where(namespaces) but surely you can put ACL for users on pages with the risk to get a looong ACL in the future ;-)
According to the two pages releases, looking for ACL, there is 19 entries in the
"old changes" page release, first entry was in 2004, and only two entries in the present
releases page. In 2012 with "Adora Belle" :
ACL now support a %GROUP% wildcard. This works like the %USER% wildcard, but for groups. :!: %USER% and %GROUP% cannot be mixed on an ACL line