Ordination procedure in Theravada Buddhism - What are grievous crimes? I read in this answer that if one wants to become a Bhikkhu then "He must never have committed any grievous crimes". 


What could examples of grievous crimes be?
What if crimes where committed many years ago. Does that have any value in the ordination procedure or does it automatically result in one not being able to become ordained in this life?


Thank you for your time.
Page 99 of this account of The
Buddhist
Monastic
Code list 11 types who should not be ordained as bhikkhus,


  
  a pandaka (essentially, a eunuch or a person born neuter—see Sanghadisesa
  2),
  a “non-human” being, (this includes nagas, petas, devas, and yakkhas),
  a hermaphrodite,
  a person who poses as a bhikkhu without having been ordained,
  a bhikkhu who has ordained in another religion without first giving up his
  status as a bhikkhu,
  a person who has murdered his father,
  a person who has murdered his mother,
  a person who has murdered an arahant,
  a person who has sexually molested a bhikkhuni,
  a person who has maliciously injured a Buddha to the point of causing him to
  bleed, and
  a person who has dishonestly caused a schism in the Sangha, knowing or
  suspecting that his position was contrary to the Dhamma-Vinaya.
  


Pages 44 through 98 describe just four parajika rules, where if a bhikkhu breaks (or has broken) one of these rules then they are automatically no longer a bhikkhu and cannot ordain again in this life:


Sexual intercourse
Stealing
Killing
Falsely claiming a superior human state