If you would like to quickly change an entry to an arbitrary TODO state instead of cycling through the states, you can set up keys for single-letter access to the states. This is done by adding the selection character after each keyword, in parentheses38. For example:
(setq org-todo-keywords '((sequence "TODO(t)" "|" "DONE(d)") (sequence "REPORT(r)" "BUG(b)" "KNOWNCAUSE(k)" "|" "FIXED(f)") (sequence "|" "CANCELED(c)")))
If you then press C-c C-t followed by the selection key, the entry is switched to this state. SPC can be used to remove any TODO keyword from an entry.
All characters are allowed except ‘@’, ‘^’ and ‘!’, which have a special meaning here.