org: Workflow states

 
 5.2.1 TODO keywords as workflow states
 --------------------------------------
 
 You can use TODO keywords to indicate different _sequential_ states in
 the process of working on an item, for example(1):
 
      (setq org-todo-keywords
        '((sequence "TODO" "FEEDBACK" "VERIFY" "|" "DONE" "DELEGATED")))
 
    The vertical bar separates the TODO keywords (states that _need
 action_) from the DONE states (which need _no further action_).  If you
 don’t provide the separator bar, the last state is used as the DONE
 state.  With this setup, the command ‘C-c C-t’ will cycle an entry from
 TODO to FEEDBACK, then to VERIFY, and finally to DONE and DELEGATED.
 You may also use a numeric prefix argument to quickly select a specific
 state.  For example ‘C-3 C-c C-t’ will change the state immediately to
 VERIFY.  Or you can use ‘S-<left>’ to go backward through the sequence.
 Completion::) or even a special one-key selection scheme (SeeFast
 access to TODO states) to insert these words into the buffer.
 Changing a TODO state can be logged with a timestamp, see SeeTracking
 TODO state changes, for more information.
 
    ---------- Footnotes ----------
 
    (1) Changing this variable only becomes effective after restarting
 Org mode in a buffer.