User groups can be created in the Vex administration page.
1. Log in to the Vex administration page.
2. Click the "Group list" button.
3. Click the "Edit" button of the group to edit.
4. In the "Edit group information" page, set the users who belong to the group, and click the "Save" button.
In addition, users belonging to "master_group" can view and operate all projects, including projects set as "Owner only".