The Abbreviations Filling Options dialog then appears.
This dialog is much simpler than the corresponding one for recurring holidays, as one-time-dates have no concept of observance or being tentative.
As always, any underscore character "_" (without the quotes) contained in this string will be replaced by a non-breaking space and that a tilde character "~" (without the quotes) contained in this string will be replaced by a normal space.
See also: filling a set with symbols.
Topic 182380, last updated on 18-Apr-2020