4. A parent who assumes more than 60% of the custody time of a child shall be considered to have sole custody for the purposes of these Rules.
Where only one parent has sole custody of all children, the support payable by the other parent shall be calculated following Division 1 of Part 5 of the form; notwithstanding the foregoing, if the non-custodial parent has visiting and prolonged outing rights, that is, if he assumes between 20% and 40% of the custody time in respect of the children, the support payable by that parent shall be calculated following Division 1.1 of that part of the form.