Permanent exile. The sentence to leave the kingdom was applied to many who had sought *sanctuary. Once the 40 days' sanctuary was over, a criminal was given the chance to abjure the realm. The guilty person was assigned a port to leave the kingdom from and a specific route to follow; the time permitted might be as little as seven days or as much as 40 days. He was dressed in a long white garment, of the kind usually worn by someone under sentence of death. He also carried a cross to show he was under protection to discourage the aggrieved from punishing the man themselves - which happened often enough.
Dictionary of Medieval Terms and Phrases. Christopher Coredon with Ann Williams.