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The last execution date in 2017 is the Wednesday, 27th of December and the last Working day the 29th. The execution for the Monday, 1st January 2018 will be moved to the last working day in December, Friday the 29th as can be seen in the next two screenshots showing part parts of the Daily Plan for 2017 and for 2018:
2017
2018
Execute on succeeding working day
With this setting the Order will be executed, for example, on the day after the first of January as shown in the next screenshot:
Ignore non-working day
This setting means, for example, that execution on the 1st of January 2018 will take place as can be seen in the screenshot below:
Mixed Behavior
Note that the screenshots shown here have been generated after changing the On Non-Working days behavior for both the 15:00 and 21:00 Periods. It could be readily conceived that there would be a use case for one Period in a Working Day that would be suppressed on Non-Working Days and another Period where execution took place regardless of the whether or not a day was Non-Working. In this case the day will be marked in the Daily Plan as an execution day and there will be no indication that not all Periods will be executed on that day.