According to Akizuki there was an older classification-system, in which the fifth category was "Kojo", "Directed upwards". This category too was meant to rid the monk of any "stink of Zen". The very advanced practitioner may also receive the "Matsugo no rokan", "The last barrier, and "Saigo no ikketsu", "The final confirmation". "The last barrier" when one left the training hall, for example "Sum up all of the records of Rinzai in one word!" It is not meant to be solved immediately, but to be carried around in order to keep practising. "the final confirmation" may be another word for the same kind of koan.