An ERP5 form in view mode usually contains 5 groups named : left, right, center,
bottom and hidden. Exception can be made for portal types with lots of
properties, like Business Template.
These groups are needed to do a proper rendering of the form. Only the "bottom"
and "hidden" groups are used in list mode. That means that "bottom" and "hidden"
are the only groups required when you are designing a form to render the
content of a module. For view mode, you need at least left, right and center;
and bottom if your view contains a listbox. The groups are defined in the 'Order'
tab of the form.