An open substitution can also be edited by preponing another period. Untis provides you with suggestions for this, as well.
The preponements are suggested in the lower part of the substitute suggestion window. The grid of the preponement suggestion shows all preponements possible to be scheduled for active substitution. You can define which period is to be provided for a possible preponement through the drop-down list. Three different settings are possible.
Preponements according to substitution grid
This (standard) setting only suggests preponements if the preponement does not cause a substitution, i.e. if it is positioned in a fringe period and therefore can be cancelled according to the substitution gird (Settings | Time grid) (in this example, as of period 7).
If every period in the substitution time grid is indicated as "to be substituted", no preponements are suggested if you defined the setting: "Shifts according to the substitution time grid".
Possible preponement suggestions are shown in the lower part of the substitute suggestion. When you click on one of the preponement suggestions, it will be visualised by red arrows in the corresponding timetables. Double click on the preponement suggestion and it will be carried out. Preponements can either have one or two steps. Two steps means that the period suggested as first preponement also causes an open substitution. In this open substitution another period is preponed.
The substitution is shown as such in the substitution view.
The "Show only upcoming shifts" setting means that only lessons are suggested as preponements which timewise come after the open substitution. Additionally, you can restrict preponement suggestions to "Show only upcoming shifts" in the >Settings>

Shifts from fringe periods
When you select: <Show shifts from fringe periods>, all fringe periods (first and last period) are provided as possible preponements regardless whether they are to be cancelled or not according to the substitution time grid.
Show all possible shifts
This setting also provides you with periods whose preponement would cause a non-teaching period (=NTP) for the class in the segment which needs to be substituted. This means that an open substitution is caused which again needs to be scheduled.
Preponements for double periods
As of Untis 2019, preponements of double periods can be regulated by only one click. Select "Period block" in the substitute suggestion. Now under step 1 and step 2, the preponement suggestion shows those periods which can be scheduled for periods 1 and 2 of the double period. Double click on the respective line and both preponements will be carried out.
Possible preponements are also visualised for double periods in the timetable, before any period is scheduled.