A multi-line style is a saved multi-line definition. You can define multi-lines styles and apply them to multi-line elements during placement. Multi-line styles can be created, customized and saved for easy recall. The Multi-line Styles dialog (Place Multi-Line tool setting window: click the ... icon next to the Style drop-down menu) is used to manage multi-line styles.
The active multi-line style is associated with the open DGN file.
Multi-line definitions can be stored as styles in either the open DGN file or a DGN library.