In principle, time slots apply independently of specific dates; they are only defined for weekdays and times. To restrict the validity to certain dates, use 
Series. Series can be used multiple times and in different contexts.
Important: In principle, times can also be entered in series. Do NOT use these times if the series is created in relation to a time slot, but ALWAYS define the times for the time slot itself.
- Click on Series >
New to open the input window. - Give the series a descriptive Name and select a validity period. The Preview window displays all the dates contained in that period.
Example: Table reservations 2025, valid from 01 Jan 2025 to 31 Dec 2025 - If necessary, enter Repetition intervals .
Example: Every week, every fortnight, every 3rd Wednesday of the month ... - If applicable, select individual Weekdays. The display in the preview window changes with each additional restriction.
- To remove individual dates from the series, select the date in the preview window by left-clicking on it and then click on
Remove. The date is moved to the left-hand window of the manually removed/added dates.
Example: Normally there are table reservations on Tuesdays, but not during the summer holidays. - In the left-hand input window, click on Add to add either individual Dates or entire Date ranges that are not covered by the series definition but should still be included.
Example: Normally there are no table reservations on Mondays, but the Mondays in December are an exception to the rule. 
Save your entry and close the window.
Important: If you previously selected weekdays for the time slot remove these settings!