diary-unknown-time

diary-unknown-time is a variable defined in `diary-lib.el'.
Its value is

-9999

Documentation:
Value returned by `diary-entry-time' when no time is found.
The default value -9999 causes entries with no recognizable time
to be placed before those with times; 9999 would place entries
with no recognizable time after those with times.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 20.3 of Emacs.