Sometimes a separator tag is added on a form view for meaningful purpose. For instance, we could have a “shipment” separator in the “sale” tab on the “party” form.
But it’s complicated if you want to add fields under this tag from distinct modules. You have to add a dependency between those modules (even if they are not) to add new field at the correct place.
Allowing to add separator tag at an higher level (i mean in a common module required by all modules that needs this separator) and hiding this separator if there’s no items under… Something equivalent to the process applied on empty pages (trytond: 5797b992383d trytond/model/modelview.py). Except that separator tag has no children like page tag.