X Heavy: Extra Heavy

X Strong: Extra strong

XX Heavy: Double extra heavy

XX Strong: Double extra strong

Y/A: York-Antwerp Rules - A code of rules adopted by an international convention in 1890, amended in 1924 and again in 1950, for the purpose of establishing a uniform basis for adjusting general average. Certain nationalities decline to observe certain of the rules adopted. United States shipping interests generally abide by general rule "F" and numbered rules 1 to 15 and 17 to 22, inclusive and specifically set this forth in a Bill Of Lading Clause.

Yield: Revenue, not necessarily profitable, per unit of traffic.