org-todo-keywords and task sequence

[David Masterson]

I'm not sure I understand 'sequence' and 'type' in org-todo-keywords.
In particular, I can only think of the following simple sequence as
being possible in org-todo-keywords:

TODO -> IN-PROCESS -> DONE

If I want to add in (say) WAITING, the graph (represented as a table)
becomes:

i\o  | TODO | IN-P | WAIT | DONE
TODO |  N   |  Y   |  N   |  N
IN-P |  N   |  N   |  Y   |  Y
WAIT |  N   |  Y   |  N   |  N
DONE |  N   |  N   |  N   |  N

This table could be more complex with more Ys or more states in the task
processing (like HOLD).  I do not see what the proper sequence(s) to use
for representing this table in Org.

Hints?

-- 
David Masterson