User Clearance

1. anonymous (clearance level:0)
2. logged in (clearance level:1)
3. registered to a page (clearance level:2)
4. owner of a page (clearance level:3)
5. root (administrator) (clearance level:4).

A user's clearance level depends on the page the user is accessing. If the page recognizes the user as a registered user or an owner, the user's clearance level changes to 2 or 3 except for the root user who always has clearance level 4 for any actions.

 example security: 
{'view':0, 
 'attachment_get':1, 
 'edit':2, 
 'create':2, 
 'delete':4, 
 'rename':3,} 

This specifies the least clearance levels required to execute actions. User can execute the action only if

 user's clearance level >= action's security level  

Security property is inherited and overrided from ancestor pages. So you only need to specify the security of actions you want to override.

For macros there is no security settings (due to caching mechanism), so the authors of macros have to be carefull not to expose protected pages.