* it should be a *list* mode listbox (it was a view mode)
* listbox column title should be the portal type name ( no written rule for this apparently )
* listbox title should be plural of portal type https://www.erp5.com/documentation/developer/guideline/module/erp5-Guideline.Module.Creation/#set-listbox-title-to-plural-of-portal-type-title-if-applicable