I also spotted this today. My hire car company - Autoway - only want the basic license details and never investigate what might be on the now nearly defunct paper bit - convictions etc. they have stored my basic details in their system and don't even ask me for any further details on each new visit with all the hire car paperwork prepared before my arrival and left in the car. Obviously more particular companies might scrutinise your licence details fully and/or ask for this 72 hour duration code. It does indeed seem a pain if you intend hiring more than 72 hours before your arrival. I doubt if many local car hire companies on Crete will bother with this but of course one never knows.
I do have to remember to update my details with this company when my licence changes on passing 70th birthday and every 3 years thereafter.
John R