54. For the purposes of Rules 55 to 57:
Operational Costs means all per diem fees and other disbursements payable to Presiding Body members for the performance of their duties as Presiding Body members, fees and disbursements of experts retained by the Presiding Body pursuant to Article 1705 and costs of third Party facilities and equipment used for meetings or hearings involving the Presiding Body.
55. Unless otherwise specified, the panel may apportion Operational Costs to the participating Parties at its discretion. In exercising its discretion, the Presiding Body may consider:
(a) whether the Disputants complied with Article 1700;
(b) the outcome of the Proceedings; and
(c) other relevant considerations that may justify assessing a major part of the responsibility for Operational Costs to one of the Disputants.
56. In the event that there are one or more Intervenors in a dispute, Operational Costs may also be apportioned among Intervenors, but in no instance shall Intervenors collectively be responsible for more than one-third of Operational Costs.
57. Nothing in these rules shall be construed as preventing a Party in its discretion from assuming full or partial liability for the share of Operational Costs for which a person of that Party is liable under Rule 55.