The ID statement specifies the variables to be displayed that further identify each activity. If two or more consecutive observations have the same combination of values for all the ID variables, only the first of these observations is plotted unless the DUPOK option is specified in the CHART statement.
By default, if the ID variables do not all fit on one page, they are all omitted and a message explaining the omission is printed to the log. You can override this behavior and display the maximum number of consecutive ID variables that can fit on a page by specifying the MAXIDS option in the CHART statement.
If the time axis of a Gantt chart spans more than one page, the ID variables are displayed only on the first page of each activity. You can display the ID variables on every page by specifying the IDPAGES option in the CHART statement.