The Custom Field Proximity pane allows you to set guest proximities based on custom field.
You can set proximities for custom fields of type Yes/No and Selection. E.g. if you have a Selection custom field "department" with values "sales", "marketing", "engineering" and "admin" you can set proximities in this pane so that the automatic seat assignment will try not to seat people in the same department together.
Note Setting proximities for custom fields may slow down the automatic seat assignment.