views_handler_relationship_groupwise_max::options_form in core/modules/views/handlers/views_handler_relationship_groupwise_max.inc

Extends the relationship's basic options, allowing the user to pick a sort and an order for it.

views_handler_relationship_node_term_data::options_form in core/modules/taxonomy/views/views_handler_relationship_node_term_data.inc

Default options form that provides the label widget that all fields should have.

views_handler_relationship_translation::options_form in core/modules/translation/views/views_handler_relationship_translation.inc

Add a translation selector.