Deemed tonnage computation rules define standards for container and break bulk arrangements and specify incidental shipping income categories. Amendment prescribes methods for computing deemed tonnage for container and break bulk arrangements, defines incidental activities treated as relevant shipping income (maritime consultancy, cargo loading/unloading, ship management fees, maritime education/recruitment), sets the formula for average net tonnage for charter in limits by dividing chartered in ton days by operated ton days, and requires the audit report for a qualified company to be furnished in Form No. 66.