Displaying diary messages in standard summary line format (usually something like ‘From Joe: Subject’) is pretty useless. Most of the time, you’re the one who wrote the message, and you mostly want to see the event’s date.
gnus-diary provides two supplemental user formats to be used in
summary line formats. D corresponds to a formatted time string
for the next occurrence of the event (e.g., “Sat, Sep 22 01, 12:00”),
while d corresponds to an approximate remaining time until the
next occurrence of the event (e.g., “in 6 months, 1 week”).
For example, here’s how Joe’s birthday is displayed in my
nndiary+diary:birthdays summary buffer (note that the message is
expirable, but will never be deleted, as it specifies a periodic event):
E Sat, Sep 22 01, 12:00: Joe's birthday (in 6 months, 1 week)
In order to get something like the above, you would normally add the following line to your diary groups’parameters:
(gnus-summary-line-format "%U%R%z %uD: %(%s%) (%ud)\n")
However, gnus-diary does it automatically (see Diary Group Parameters). You can however customize the provided summary line format
with the following user options:
Defines the summary line format used for diary groups (see Summary Buffer Lines). gnus-diary uses it to automatically update the
diary groups’parameters.
Defines the format to display dates in diary summary buffers. This is
used by the D user format. See the docstring for details.
Defines the format function to use for displaying delays (remaining
times) in diary summary buffers. This is used by the d user
format. There are currently built-in functions for English and French;
you can also define your own. See the docstring for details.