Creating combined fragments in sequence diagrams

In sequence diagrams, you can create combined fragments to visually represent control structures, such as a for-loop or if-else statements, in interactions. Combined fragments can contain interaction operands, guard conditions and other combined fragments. Combined fragments contain procedural logic that control the messages inside the combined fragment.

Before you begin

You must have a sequence diagram open that contains lifelines.


  1. In the Palette, click a type of combined fragment.
  2. In the editor, click in the interaction frame.
  3. Drag the combined fragment across the elements that you want it to include.


The covered messages and interaction fragments are displayed in the first interaction operand of the combined fragment.

When you create a combined fragment, the interaction operand can be collapsed to hide the operand and its associated messages and interaction fragments to minimize the size of the combined fragment in the interaction frame.

You can create nested combined fragments by adding one combined fragment inside another. To nest a combined fragment, the source combined fragment cannot contain a create or a destroy message.