ATM Sequence diagram

This example of automated teller machine (ATM) UML sequence diagram was created on the base of figure 5 "Sequence diagram" on the webpage "Message Sequence Charts and their Ilk" from the website of the University of California Irvine (UCI) Donald Bren School of Information and Computer Sciences.
"A UML sequence diagram or SD is similar to an MSC but written with a different notation. Presumably the same semantic issues arise, but possibly not since UML semantics are not well-defined. An example is shown in Figure 5.
The timelines are dotted rather than solid, and the name of the component is inside a box at the head of each timeline. The narrow rectangles apparently show when a component is active (unsure precisely what "active" means). An X on a timeline indicates that the component ceases to exist in some sense (unsure precisely how this is meant also). In the example, the Bank timeline has an X simply as an example (presumably the Bank does continue to exist)."
[www.ics.uci.edu/ ~alspaugh/ cls/ shr/ msc.html]
This example of bank ATM sequence diagram was created using the ConceptDraw PRO diagramming and vector drawing software extended with the ATM UML Diagrams solution from the Software Development area of ConceptDraw Solution Park.