In some monthly diaries, you do not wish to hide outside days, but you wish to show them differently, as shown below, for example.
The trick is to set the outside days option to show, but place a zap token, for example [1zd>8], that deletes the black textbox if its date is greater than 8. Since dates in the first row of the current month can at most range from 1 to 7, any date greater than 8 must come from the previous month.
The opposite zap condition, for example [32zd<8], is used for dates at the end of the month.
See also: other tokens tips and tricks.