The register ton is a unit of volume in the shipping world and uses the symbol GRT.
1 register ton is equal to 100 ft³ or 2.832 m³.
The register ton is used in shipping to measure the amount of cargo on a vessel. The phrase is often mistaken for a unit of mass or weight because of the term 'ton' but should not be confused.
The US fluid ounce is a unit of volume in the US customary unit system with the symbol fl oz.
Primarily used for measuring the volume or capacity of liquids, 1 US fluid ounce is equal to 29.57353 ml. It is also equal to 1.040843 imperial fluid ounces.
1 US fluid ounce is equal to 1/16 imperial pint, 1/32 imperial quart and 1/128 imperial gallon.
The fluid ounce was originally defined by the volume taken up by one ounce of a substance. Of course this would be different depending on the density of that substance; for example England used wine whereas Scotland used water to establish this measure.
The US fluid ounce is derived from the US gallon; which was originally based on the English wine gallon (231 cubic inches).