In UML diagrams, an interaction frame provides a context or boundary in which you create diagrams and observe behavior.
As the following figure illustrates, in UML, a frame is displayed as a rectangular box with a heading label, or pentagon descriptor figure, at the top left corner.
In sequence diagrams, the heading label of the interaction frame consists of text which is the name of the interaction that the interaction frame represents.
The frame and its contents represent interaction in sequence diagrams. You can nest a frame inside another frame or diagram. The enclosing diagram then reuses the entire enclosed diagram inside the new context. In sequence diagrams, a frame can represent combined fragments, which represent scenario constructs, and interaction occurrences, which represent an interaction within an interaction.