                     heading)
       (match-string 4 heading))))
 
-(defcustom timeline-short-task-threshold 300
-  "Duration of task to be considered as short."
-  :group 'timeline-reporting
-  :type 'integer)
-
 (defun db/org-format-timeline (tstart tend &optional files)
-  "Display timeline of tasks in FILES between TSTART and TEND.
+  "Display timeline of tasks between TSTART and TEND from FILES.
+
 When not given, FILES defaults to `org-agenda-files’.  Short
 slots are removed, and afterwards slots are clusted by category.
 When called interactively, START and END are queried with

            (save-mark-and-excursion
             (funcall headline-fn)))))))))

(defun db/org-clocking-time-in-range (tstart tend)
  "Return list of all tasks in the current buffer together with
their clocking times that are between TSTART and TEND.  The
resulting list consists of elements of the form

  (MARKER . CLOCK-TIMES)


    clock-lines))

(defun db/org-copy-clock-lines (source-id target-id)
  "Copy clock lines from SOURCE-ID to TARGET-ID.

Both SOURCE-ID and TARGET-ID must designate known `org-mode’
tasks by their ID.  Copies all clock lines attached to SOURCE-ID
or to one of its subtree, and adapts the clock lines in the file
of TARGET-ID accordingly."
  (let ((source-marker (org-id-find source-id :get-marker))
        (target-marker (org-id-find target-id :get-marker)))
    (cl-assert (markerp source-marker)
