I would create two tables; users and ranks.
User
-----
id
username
rankID
Ranks
------
id
makeChanges
acceptChanges
changePermissions
view
Then just create the various ranks that you want in the Ranks table and set the rankID of the users to match the corresponding one that you want. Make sure to set in the Ranks table each field to a value of 0 or 1; with 0 being not having that ability and 1 having that option.
Edit If you were going to do this without a database then you could give do it with the classes or even instances in PHP5. For instance, let's say that you had set a name for each of the things that you had in your original post:
Creator - make changes, accept changes, change permissions
Reviewer - Accept changes
Editor - Make changes
Regular - View
Then you could do something like below. (The database way would obviously be a much better way, but this is just an example.)
class Regular
{
public function View()
{
//Do the view stuff in here
}
}
class Editor extends Regular implements Edit
{
}
class Reviewer extends Regular implements Review
{
}
interface Review
{
public function AcceptChanges()
{
//Do the accept changes here
}
}
interface Edit
{
public function MakeChanges()
{
//Do the make changes stuff here
}
}
class Creator extends Regular implements Edit, Review
{
public function ChangePermissions()
{
//Do the change permissions stuff here
}
}