Correct optionalities are identified using dotted lines and solid lines correct degrees of relationships are marked 關(guān)系的強制性須由虛線及實線正確地加以辨明。
All relationships which are ended in the same group of exclusion have the same optionalities . exclusive arcs are not marked at one single relationship lines, but for a group of two or more relationshiplines 專用弧號不會在單一條關(guān)系線上加以專用的標示,它只會在一組具有兩條或以上的關(guān)系線上才標示出來。