Although there's a very outdated page explaining User Levels, the explanation given is quite useless:
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User levels (0-10) are almost completely deprecated in versions 0.9.2+.
Most of what a user can do or cannot do is controlled by the User permissions.
Starting with version 2.0, User with a higher level can be given permissions to edit posts by users of lower level, or of equal level.
In previous versions here is what user levels would allow:
* Level 1 and above:
o Ability to view link to admin section (users with level 0 can still login into admin, but there's no good reason for that, except in rare cases, so they'll have to find out by themselves...) (on versions < 0.9.2).
o Ability to upload images (on versions < 0.9.2).
* Level 2 and above:
o Ability to generate static pages (on versions < 2.0 -- In 2.0 ability to generate static pages is granted to anyone with any post permission.).
* Level 5 and above:
o Ability to edit timestamp on posts and comments.
Why is it necessary to have 10 levels? Or, if 10 levels are necessary why isn't there a complete, decent, explanation for each level?
Also, when lowest the level, the simplest the user's backoffice should be. Nothing more and nothing less of what the user can do should appear in the evobar o menu bar, which by the way, are redundant.