We use this page when we want to assign one or more users to a role.
On the left side of the page there is a list containing all the defined roles. By clicking on each role, on the right side of the page, we see a list that related to the users assigned to the selected role.
If we want to remove a user from the selected role, select the checkbox related to the user name and then click on the 
.
If we want to add a new user to the desired role, we click on the 
. In the opened list, check the box(s) related to the user(s) and finally click 
.