A Time Scale symbol indicates the period over which the Project development is shown.
The length of the Time Scale symbol will determine the length of the Project Time Bar symbols and the positioning of the Milestone symbols. The Time Scale symbol is therefore mandatory and should be placed in a default location on the diagram when a new diagram is created. A convenient default location is indented from the left edge of the diagram to allow Project rectangle symbols to be placed in the margin.
As Projects are added, the Time Scale should automatically move down the screen to accommodate them.
The Time Bar symbol can be stretched to the right by the user. Changing the rightmost end of the Time Scale symbol forces the Project Time Bars to stretch in a corresponding way, as well as to force the Milestone symbols to be relocated. The user is allowed to stretch the Time Bar, but this just changes its (and the diagram’s) Projects’ geometrical extent. The timescale of the Time Bar is controlled by its symbol properties.
The units used for the Time Scale will be made available for selection by the user through a symbol property. The units will be Years, Quarters, Months, Weeks and Days.
The interval on the scale will be made available for specification by the user through a symbol property.
The Time Bar symbol also has properties recording the start date and the end date.
▪Milestone instances falling outside of the chronological extent of the Time Bar are simply not drawn. Projects are always drawn over the same extent as the Time Bar.
▪System Architect Date properties will be sufficient for recording timescales; a separate datetime field will not be needed.
▪If start date is blank it is assumed to be the 1st of January of the current year.
▪If end date is blank or less than the start date it is assumed to be exactly one year on from the start date.
▪If interval number is blank it is assumed to be 1.