Timeline diagram

Timeline charts presents events and time periods on a chronological scale. They are used in project management to visualize project milestones and upper level phases, and show project progress.
"Within the framework of project management, a milestone is an event that receives special attention. It is often put at the end of a stage to mark the completion of a work package or phase. Milestones can be put before the end of a phase so that corrective actions can be taken, if problems arise, and the deliverable can be completed on time.
In addition to signaling the completion of a key deliverable, a milestone may also signify an important decision or the derivation of a critical piece of information, which outlines or affects the future of a project. In this sense, a milestone not only signifies distance traveled (key stages in a project) but also indicates direction of travel since key decisions made at milestones may alter the route through the project plan." [Milestone (project management). Wikipedia]
This timeline diagram example was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Timeline Diagrams solution from the Management area of ConceptDraw Solution Park.

The vector stencils library "UML timing diagrams" contains 15 symbols for the ConceptDraw PRO diagramming and vector drawing software.
"The following nodes and edges are typically drawn in a UML timing diagram: lifeline, state or condition timeline, destruction event, duration constraint, time constraint. ...
Lifeline is a named element which represents an individual participant in the interaction. ... lifelines represent only one interacting entity. ...
Lifeline on the timing diagrams is represented by the name of classifier or the instance it represents. It could be placed inside diagram frame or a "swimlane". ...
Timing diagram could show states of the participating classifier or attribute, or some testable conditions, such as a discrete or enumerable value of an attribute. ...
UML also allows the state/ condition dimension be continuous. It could be used in scenarios where entities undergo continuous state changes, such as temperature or density. ...
Destruction occurrence is a message occurrence which represents the destruction of the instance described by the lifeline. It may result in the subsequent destruction of other objects that this object owns by composition. No other occurrence may appear after the destruction event on a given lifeline.
Complete UML name of the occurrence is destruction occurrence specification. Until UML 2.4 it was called destruction event, and earlier - stop.
The destruction event is depicted by a cross in the form of an X at the end of a timeline. ...
Duration constraint is an interval constraint that refers to a duration interval. The duration interval is duration used to determine whether the constraint is satisfied.
The semantics of a duration constraint is inherited from constraints. If constraints are violated, traces become negative which means that system is considered as failed.
Duration constraint is shown as some graphical association between a duration interval and the constructs that it constrains. ...
Time constraint is an interval constraint that refers to a time interval. The time interval is time expression used to determine whether the constraint is satisfied.
The semantics of a time constraint is inherited from constraints. All traces where the constraints are violated are negative traces, i.e., if they occur, the system is considered as failed.
Time constraint is shown as graphical association between a time interval and the construct that it constrains. Typically this graphical association is a small line, e.g., between an occurrence specification and a time interval." [uml-diagrams.org/ timing-diagrams.html]
The example "Design elements - UML timing diagrams" is included in the Rapid UML solution from the Software Development area of ConceptDraw Solution Park.