diary-display-function is a variable defined in `diary-lib.el'.
Its value is

  • This variable may be risky if used as a file-local variable.

Function used to display the diary.
The two standard options are `diary-fancy-display' and `diary-simple-display'.

When this function is called, the variable `diary-entries-list'
is a list, in order by date, of all relevant diary entries in the
form of ((MONTH DAY YEAR) STRING), where string is the diary
entry for the given date. This can be used, for example, to
produce a different buffer for display (perhaps combined with
holidays), or hard copy output.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 23.2 of Emacs.