Since the spring of 2018, the results shown below can be achieved, much more simply and easily, using the minicalendar text framing and shading options and QuarkXPress 2017 and above.
The information below should only be used to maintain existing, pre-2018 diaries, or if you are not yet using QuarkXPress 2017.
The Show only on Holidays minicalendar modifier, denoted by :Hol1 and :Hol2, can be used to specify that only those dates corresponding to holidays of the lists specified in either of the holidays minicalendar options should be displayed.
This option is usually used to display a box, oval, circle, frame, ..., to highlight the dates when a holiday occurs, as shown in the example below :
To obtain the result shown above (white text on a red oval), you would use 2 minicalendar textboxes, one on top of the other (the 2 textboxes are shown side-by-side, below, to make the picture more legible).
The minicalendar textbox on the right [1mc+00:Hol1-alt1] uses a minicalendar token that uses a Show only on Holidays Minicalendar Modifier and the indication that on those dates the dates should be displayed using the following alternate font formatting (the -alt2 modifier is also available):
Note that the numbers corresponding to the dates of current days are replaced by a constant character in a symbol-like font, on every holiday date, regardless of it value. This is quite typical of the use of the Show only on Holidays Minicalendar Modifier.