Parking brake left set.
In the fifty and some years that I have been involved in aviation, as a ground engineer, flight engineer and pilot I cannot ever recall a normal requirement to leave the brakes applied after having the chocks in place. That applies to all the aircraft I have been associated with from light aircraft to B747's. I am not questioning the posts of those such as mudackace or Feather #3, just a little surprised that their company uses such practice.