Variable: timeclock-use-24hr-format
timeclock-use-24hr-format is a customizable variable defined in
timeclock.el.gz.
Value
nil
Documentation
If non-nil, use 24-hour clock when displaying times.
Otherwise use 12-hour clock with AM/PM suffix.
Probably introduced at or before Emacs version 32.1.
Source Code
;; Defined in /usr/src/emacs/lisp/calendar/timeclock.el.gz
(defcustom timeclock-use-24hr-format nil
"If non-nil, use 24-hour clock when displaying times.
Otherwise use 12-hour clock with AM/PM suffix."
:type 'boolean)