Abstract: An automatic relationship selector can be used with complex visualized modeling languages, such as Unified Modeling Language, to help users obtain appropriate relationship types for connectors. The selector automatically selects a connector relationship type based on relationship selection criteria which may include element types, an implicit default, an explicit default, and/or a heuristic default. A user can manually override automatically selected connector relationship type assignments. A helper lets a user set aggregation and other connector relationship properties. Automatic relationship type selection is done in-place while a connector is being positioned, to maintain the user interface's focus on the design diagram and avoid interrupting the user's design drafting flow.