# Life Lines
# ----------

# A lifeline is a vertical dashed line that appears below a participant’s name
# (usually inside a rectangle at the top). It shows the existence of that
# participant over time, starting from the top (earlier in time) and extending
# downward as time progresses.

# Structure of a Lifeline
# 
# - Actor box (head): Contains the name of the object or actor.
#
# - Vertical dashed line: Represents the object’s presence throughout the
#   interaction.
#
# - Executions bars (optional): Narrow rectangles over the lifeline that show
#   when the object is performing an action or is active (e.g., executing a
#   method). These are alternatively called: Activations or Invocations

actor : actor
boundary : boundary
control : control
entity : entity
type : type

object : "Life Line"

ref(Sequence Diagrams | /diagrams/uml-sequence-diagrams )

object.create()
object.method(method parameters) {
  return(method results)
}
object.destroy()

note(460, 10, 200, The box or icon at the top of the life line shows the objects name and its class/classifier. )
note(440, 120, 200, Actors/objects exist by default or can be created explicitly using the create message )
note(570, 280, 200, Execution rectangles show the time taken to perform an action. )
note(570, 370, 200, Cross shows the end of the actors life. )